• Home
  • Textbooks
  • Guide to Physics IIT JEE
  • Newton's Law of Motion

Guide to Physics IIT JEE

Ravi Raj Dudeja

Chapter 5

Newton's Law of Motion - all with Video Answers

Educators

Chapter Questions

02:18

Problem 1

A toy train consists of three identical compartments $A$, $B$ and $C$. It is being pulled by a constant force $F$ along C. The ratio of the tension in the string connecting $A B$ and $B C$ is
(a) $2: 1$
(b) $1: 3$
(c) $1: 1$
(d) $1: 2$

Sachin Rao
Sachin Rao
Numerade Educator
01:11

Problem 2

A block of mass $\mathrm{M}$ is pulled along a smooth horizontal surface with a rope of mass $m$. The acceleration of the block will be
(a) $\mathrm{F} /(\mathrm{M}+m)$
(b) $\mathrm{F} /(\mathrm{M}-m)$
(c) $\mathrm{F} / \mathrm{M}$
(d) $\mathrm{F} / m$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:39

Problem 3

A body of weight $50 \mathrm{~N}$ is dragged on a horizontal surface with a force of $28.2 \mathrm{~N}$. The frictional force acting on the body and the normal reactional force will be
(Figure can't copy)
(a) $2 \mathrm{~N}, 3 \mathrm{~N}$
(b) $5 \mathrm{~N}, 7 \mathrm{~N}$
(c) $10 \mathrm{~N}, 15 \mathrm{~N}$
(d) $20 \mathrm{~N}, 30 \mathrm{~N}$

Manish Kumar
Manish Kumar
Numerade Educator
01:01

Problem 4

Two blocks of mass $4 \mathrm{~kg}$ and $2 \mathrm{~kg}$ are placed in contact with each other on a frictionless horizontal surface. If we apply a push of $5 \mathrm{~N}$ on the heavier mass, the force on the lighter mass will be
(a) $2 \mathrm{~N}$
(b) $4 \mathrm{~N}$
(c) $5 \mathrm{~N}$
(d) none of these

Raj Bala
Raj Bala
Numerade Educator
02:02

Problem 5

A jar containing water is placed in a train. The train accelerates from left to right. Which of the following shows the water level in a jar correctly?
(Figure can't copy)

Vysakh M
Vysakh M
Numerade Educator
01:11

Problem 6

A block of mass $m$ is placed on a smooth inclined plane of inclination $\theta$ with the horizontal. The force exerted by the plane on the block has magnitude
(a) $m g \tan \theta$
(b) $m g \cos \theta$
(c) $m g / \cos \theta$
(d) $m g$

Ajay Singhal
Ajay Singhal
Numerade Educator
02:23

Problem 7

The work done in dragging a block of mass $5 \mathrm{~kg}$ on an inclined plane of height $2 \mathrm{~m}$ is 150 Joule. The work done against the frictional force will be
(a) 200 Joule
(b) 150 Joule
(c) 100 Joule
(d) 50 Joule

Yuva S
Yuva S
Numerade Educator
01:11

Problem 8

Two masses $m$ and $M$ are lying on a surface moving with acceleration $a$. Only the given supporting and moving surface has coefficient of friction as $\mu$. The frictional forces for $\mu>a / g$ and $\mu<a / g$ are
(Figure can't copy)
(a) $m a, m a$
(b) $m a, \mu m g$
(c) $\mu m g$, $\mu m g$
(d) $\mu m g, m a$

David González Cornejo
David González Cornejo
Numerade Educator
01:24

Problem 9

A small sphere of mass $m$ is attached to a spring of spring factor $k$ and normal length $l$. If the sphere rotates with radius $r$ at frequency $v$ then tension in the spring is
(Figure can't copy)
(a) $k^2 l$
(b) $k^2(r-l)$
(c) $m r(2 \pi v)^2$
(d) $k l$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
02:53

Problem 10

Two masses each equal to $m$ are lying on $x$-axis at ( $-a$, $0)$ and $(+a, 0)$ respectively. They are connected by a light string. A force $F$ is applied at the origin along $y$ axis resulting into motion of masses towards each other. The acceleration of each mass when position of masses at any instant becomes $(-x, 0)$ and $(+x, 0)$ is given by
(a) $\frac{F}{m} \frac{x}{\sqrt{a^2-x^2}}$
(b) $\frac{F}{m} \frac{\sqrt{a^2-x^2}}{x}$
(c) $\frac{F x}{2 m \sqrt{a^2-x^2}}$
(d) $\frac{F}{2 m} \sqrt{\frac{a^2-x^2}{x}}$
(Figure can't copy)

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
02:12

Problem 11

A particle of mass $m$ is suspended from a fixed point $O$ by a string of length $l$. At $t=0$, it is displaced from equilibrium position and released. The graph which shows the variation of tension $T$ in string with time $t$ is
(Figure can't copy)

Suzanne W.
Suzanne W.
Numerade Educator
03:37

Problem 12

Two blocks of masses $m_1$ and $m_2$ are connected to each other with the help of a spring. If pushing force is given to mass $m_1$ providing acceleration $a$ to it, then acceleration of $m_2$ is
(Figure can't copy)
(a) $\frac{m_1 a-F}{m_2}$
(b) $\frac{F-m_1 a}{m_2}$
(c) a
(d) $\frac{F-m_1 a}{m_1}$

Vysakh M
Vysakh M
Numerade Educator
01:45

Problem 13

A stone weighing $1 / 2 \mathrm{~kg}$ is tied to a string $1 / 2 \mathrm{~m}$ long having withstand capacity of $20 \mathrm{~kg}$. The stone is in horizontal circular motion over a frictionless table with a speed of $1.5 \mathrm{~ms}^{-1}$. If tension in the string is equal to the breaking force of the spring, the speed attained is
(Figure can't copy)
(a) $14 \mathrm{~ms}^{-1}$
(b) $11 \mathrm{~ms}^{-1}$
(c) $24 \mathrm{~ms}^{-1}$
(d) $17 \mathrm{~ms}^{-1}$

Vysakh M
Vysakh M
Numerade Educator
05:41

Problem 14

A body takes $n$ times, the time to slide down a rough inclined plane as it takes to slide down the same inclined plane when it is perfectly frictionless. The coefficient of kinetic friction between the body and the plane for an angle of inclination of $45^{\circ}$ is given by $\mu$
(a) $1-\frac{1}{n}$
(b) $\frac{1}{n}$
(c) $\left(1-\frac{1}{n^2}\right)$
(d) $\left(\frac{1}{n^2}-1\right)$

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
03:06

Problem 15

Two blocks of masses $2 \mathrm{~kg}$ and $5 \mathrm{~kg}$ are at rest on ground. The masses are connected by a string passing over a frictionless pulley which is under the influence of a constant upward force $F=50 \mathrm{~N}$. The accelerations of $5 \mathrm{~kg}$ and $2 \mathrm{~kg}$ masses are
(Figure can't copy)
(a) $0,2.5 \mathrm{~ms}^{-2}$
(b) 0,0
(c) $2.5 \mathrm{~ms}^{-2}, 2.5 \mathrm{~ms}^{-2}$
(d) $1 \mathrm{~ms}^{-2}, 2.5 \mathrm{~ms}^{-2}$

Aniket Bajaj
Aniket Bajaj
Numerade Educator
02:20

Problem 16

A body starts to slide from $P$, down an inclined frictionless plane $P Q$ having inclination $\alpha$ with horizontal and then ascends another smooth inclined plane $Q R$ with angle of inclination $2 \alpha$. Neglecting impact at $O$
(a) $t_{P Q}=t_{Q R}$
(b) $t_{P Q}<t_{Q h}$
(c) $h^{\prime}=2 h$
(d) $h^{\prime}=h$
(Figure can't copy)

Prabhu Ramji
Prabhu Ramji
Numerade Educator
03:25

Problem 17

A rod of length $L$ is rotated in horizontal plane with constant angular velocity $\omega$ A mass $m$ is suspended by a light string of length $L$ from the other end of the rod. If the angle made by vertical with the string is $\theta$ then angular speed, $\omega=$
(Figure can't copy)
(a) $\left[\frac{g \sin \theta}{L(1+\tan \theta)}\right]^{\frac{1}{2}}$
(b) $\left[\frac{L(1+\tan \theta)}{g \tan \theta}\right]^{\frac{1}{2}}$
(c) $\left[\frac{g \tan \theta}{L+\sin \theta}\right]^{\frac{1}{2}}$
(d) $\left[\frac{g \tan \theta}{L(1+\sin \theta)}\right]^{\frac{1}{2}}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
05:30

Problem 18

A stone of mass $1000 \mathrm{~g}$ tied to a light string of length $10 / 3 \mathrm{~m}$ is whirling in a vertical circle. If the ratio of the maximum tension to minimum tension is 4 and $g=10$ $\mathrm{ms}^{-2}$, then speed of stone at the highest point of circle is
(a) $20 \mathrm{~ms}^{-1}$
(b) $10 / \sqrt{3} \mathrm{~ms}^{-1}$
(c) $5 \sqrt{3} \mathrm{~ms}^{-1}$
(d) $10 \mathrm{~ms}^{-1}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
07:27

Problem 19

A man tries to remain in steady state by pushing his feet and hands against two parallel walls. Then for equilibrium
(Figure can't copy)
(a) force of friction should be equal on the two walls.
(b) force exerted by him on both walls should be equal and the walls should not be frictionless.
(c) he should press his feet with greater force.
(d) coefficient of friction should be equal for both walls.

Cyra Jelle Calleja
Cyra Jelle Calleja
Numerade Educator
03:06

Problem 20

A block of mass $1 \mathrm{~kg}$ is connected by a light string passing over two smooth pulleys placed on a smooth horizontal surface as shown. Another block of $1 \mathrm{~kg}$ is connected to the other end of the string then acceleration of the system and tension in the string are
(Figure can't copy)
(a) $5 \mathrm{~ms}^{-2}, 5 \mathrm{~N}$
(b) $1 \mathrm{~ms}^{-2}, 1 \mathrm{~N}$
(c) $1 \mathrm{~ms}^{-2}, 5 \mathrm{~N}$
(d) $5 \mathrm{~ms}^{-2}, 10 \mathrm{~N}$

Aniket Bajaj
Aniket Bajaj
Numerade Educator
03:04

Problem 21

A mass of $2 \mathrm{~kg}$ is placed on a trolley of $20 \mathrm{~kg}$ sliding on a smooth surface. The coefficient of friction between the mass and surface of trolley is 0.25 . A horizontal force of $2 \mathrm{~N}$ is applied to the mass. The acceleration of the system and the frictional force between the mass and surface of trolley are
(Figure can't copy)
(a) $1.8 \mathrm{~ms}^{-2}, 0.09 \mathrm{~N}$
(b) $0.9 \mathrm{~ms}^{-2}, 18 \mathrm{~N}$
(c) $0.09 \mathrm{~ms}^{-2}, 1.8 \mathrm{~N}$
(d) $1 \mathrm{~ms}^{-2}, 2 \mathrm{~N}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:01

Problem 22

Three blocks of masses $3 \mathrm{~kg}, 6 \mathrm{~kg}$ and $1 \mathrm{~kg}$ are connected by a string passing over two smooth pulleys attached at the two ends of a frictionless horizontal surface. The acceleration of $3 \mathrm{~kg}$ mass is
(Figure can't copy)
(a) $1 \mathrm{~ms}^{-2}$
(b) $2 \mathrm{~ms}^{-2}$
(c) $3 \mathrm{~ms}^{-2}$
(d) $4 \mathrm{~ms}^{-2}$

Raj Bala
Raj Bala
Numerade Educator
02:32

Problem 23

A pearl of mass $m$ is in a position to slide over a smooth wire. At the initial instant the pearl is in the middle of the wire. The wire moves linearly in a horizontal plane with an acceleration $a$ in a direction having angle $\theta$ with the wire. The acceleration of the pearl with reference to wire is
(a) $g \sin \theta-a \cos \theta$
(b) $g \sin \theta-g \cos \theta$
(c) $g \sin \theta+a \cos \theta$
(d) $g \cos \theta+a \sin \theta$
(Figure can't copy)

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:50

Problem 24

A mass is resting on a rough plank. At initial instant a horizontal impulse is applied to the mass. If the velocity of mass at instant $t$ is $v$ and displacement upto this instant is $S$ then correct graph is
(Figure can't copy)

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
01:01

Problem 25

A straight tube of length $L$ contains incompressible liquid of mass $M$ and the closed tube is whirled in horizontal plane about one of the ends. If $\omega$ is the uniform angular velocity, the force exerted by the liquid on the other end is
(Figure can't copy)
(a) $\frac{M L \omega^2}{4}$
(b) $2 M L \omega^2$
(c) $\frac{M L \omega^2}{4}$
(d) $M L \omega \sigma^2$

Narayan Hari
Narayan Hari
Numerade Educator
04:47

Problem 26

A light rope passes over a pulley. One section of the rope is held by a child and the other section by a man, then
(Figure can't copy)
(a) the man and the child have same vector acceleration.
(b) the man and the child have same magnitude of acceleration but in opposite direction.
(c) the man and the child have different magnitude of acceleration.
(d) the man and the child have accelerations which keep on interchanging with each other.

Prabhu Ramji
Prabhu Ramji
Numerade Educator
01:16

Problem 27

A trolley is under the action of a constant force $F$. The sand contained by it is poured out through a hole in the floor at the rate of $m$ per second. If initial mass of sand and trolley was $M$ and initial speed was $u$, then acceleration of trolley is given by
(Figure can't copy)
(a) $\frac{F}{M-m t}$
(b) $\frac{F}{M+m t}$
(c) $\frac{F}{M-m}$
(d) $\frac{F}{M+m}$

Narayan Hari
Narayan Hari
Numerade Educator
00:50

Problem 28

A smooth track of incline of length $l$ is joined smoothly with circular track of radius $R$. A mass of $m \mathrm{~kg}$ is projected up from the bottom of the inclined plane. The minimum speed of the mass to reach the top of the track is given by, $v=$
(a) $[2 g(l \cos \theta+R)(1+\cos \theta)]^{1 / 2}$
(b) $(2 g l \sin \theta+R)^{1 / 2}$
(c) $[2 g\{1 \sin \theta+R(1-\cos \theta)\}]^{1 / 2}$
(d) $(2 g l \cos \theta+R)^{1 / 2}$
(Figure can't copy)

Hast Aggarwal
Hast Aggarwal
Numerade Educator
01:50

Problem 29

A massless string of length $l$ passes over a frictionless pulley with horizontal axis. Two monkeys hang from the ends of the string at the same distance $l / 2$ from the pulley, the monkeys start climbing upwards simultancously. First monkey climbs with a speed $v$ relative to the string and the second with speed of $2 v$ Both monkeys have got same masses. The time taken by the first and second monkeys in reaching the pulleys are respectively.
(Figure can't copy)
(a) $\left(\frac{1}{v}\right),\left(\frac{1}{2 v}\right)$
(b) $\sqrt{\frac{2 l}{v}}, \sqrt{\frac{l}{v}}$
(c) $\left(\frac{l}{2 v}\right)^{\frac{1}{2}},\left(\frac{1}{v}\right)^{1 / 2}$
(d) $\left(\frac{1}{3 v}\right),\left(\frac{1}{3 v}\right)$

Ajay Singhal
Ajay Singhal
Numerade Educator
02:14

Problem 30

Neglecting the masses of the string and pulley and ignoring the friction in the system, we find that
(Figure can't copy)
(a) weights fall freely. Pulley $B$ rotates clockwise and pulley $A, C$ rotate anticlockwise.
(b) the two weights have different accelerations. Pulley $C$ rotates clockwise and $B, C$ rotate anticlockwise.
(c) acceleration of masses will be zero and the system will be at rest.
(d) acceleration of masses is equal to $g$. Pulley $A$ and $C$ rotate elockwise whereas $B$ rotates anticlockwise.

Surendra Kumar
Surendra Kumar
Numerade Educator
04:16

Problem 31

A simple pendulum is vibrating with an angular amplitude of $\frac{\pi}{2}$. The value of $\alpha$ for which the resultant acceleration has a direction along the horizontal is
(Figure can't copy)
(a) $\frac{\pi}{2}$
(b) $180^{\circ}$
(c) $\cos ^{-1}\left(\frac{1}{\sqrt{3}}\right)$
(d) $\cos ^{-1}\left(\frac{1}{\sqrt{2}}\right)$

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
02:21

Problem 32

A body of mass $m$ starting from rest slides down a frictionless inclined surface of gradient $\alpha$ fixed on the floor of a lift accelerating upward with acceleration $a$. Taking width of inclined plane as $W$, the time taken by body to slide from top to bottom of the plane is
(Figure can't copy)
(a) $\left(\frac{2 W}{(g+a) \sin \alpha}\right)^{\frac{1}{2}}$
(b) $\left(\frac{4 W}{(g-a) \sin \alpha}\right)^{\frac{1}{2}}$
(c) $\left(\frac{4 W}{(g+a) \sin 2 \alpha}\right)^{\frac{1}{2}}$
(d) $\left(\frac{W}{(g+a) \sin 2 \alpha}\right)^{\frac{1}{2}}$

Prem Bijarniya
Prem Bijarniya
Numerade Educator
01:24

Problem 33

A very small mass $m$ is fixed to one end of a massless spring of constant $k$ and normal length $l$. The spring and the mass are rotated about the other end of the spring with angular speed $\omega$. Neglect the effect of gravity. Extension in the spring is
(Figure can't copy)
(a) zero
(b) $\frac{m / \omega^2}{k+m \omega^2}$
(c) $m l \omega^2$
(d) $\frac{m \omega^2 l}{k-m \omega^2}$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
02:50

Problem 34

A rope is stretched between two boats at rest. A sailor in the first boat pulls the rope with a constant force of 100 N. First boat with the sailor has a mass of $250 \mathrm{~kg}$ whereas the mass of second boat is double of that mass. If the initial distance between the boats was $100 \mathrm{~m}$, the time taken for two boats to meet each other is
(Figure can't copy)
(a) $13.8 \mathrm{~s}$
(b) $18.3 \mathrm{~s}$
(c) $3.18 \mathrm{~s}$
(d) $31.8 \mathrm{~s}$

RZ
Rubeena Zulfiqar
Numerade Educator
01:51

Problem 35

A block of mass $M$ is situated on a smooth horizontal table. A thread tied to the block passes through a hole in the table and carries a mass $m$ at its other end. If the length of thread above the table is $/$ and $M$ is revolving in horizontal circle with angular speed $\omega$ on the table, then value of $m$ so that it remains suspended at a constant height $h$ is
(Figure can't copy)
(a) $M g h \omega^2$
(b) $M g l \omega^2$
(c) $\frac{M l \omega^2}{g}$
(d) $M I \omega^2$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
01:30

Problem 36

A parachute of mass $m$ starts coming down with a constant acceleration $a$. Determine the ballast mass to be released for the parachute to have an upward acceleration of same magnitude. Neglect air drag.
(a) $\frac{2 m a}{a+g}$
(b) $\frac{m a}{a-g}$
(c) $\frac{m a}{a+g}$
(d) $\frac{2 m a}{a-g}$

Ajay Singhal
Ajay Singhal
Numerade Educator
05:08

Problem 37

Block $A$ is placed on block $B$ (mass of $B>$ mass of $A$ ). There is friction between the blocks but the ground is frictionless. A horizontal force $F$, increasing linearly with time, begins to act on $A$. Accelerations $a_v$ and $a_s$ of blocks $A$ and $B$ respectively is correctly plotted as
(Figure can't copy)

Eric Mockensturm
Eric Mockensturm
Numerade Educator
03:15

Problem 38

A circular table has a radius of $1 \mathrm{~m}$ and mass $20 \mathrm{~kg}$. It has 4 legs of $1 \mathrm{~m}$ each fixed symmetrically on its circumference. The maximum weight which can be placed anywhere on this table without toppling it is
(a) $84.3 \mathrm{~kg}$
(b) $34.8 \mathrm{~kg}$
(c) $48.3 \mathrm{~kg}$
(d) $43.8 \mathrm{~kg}$
(Figure can't copy)

Vidhi Bhatt
Vidhi Bhatt
Numerade Educator
02:33

Problem 39

A board is balanced on a rough horizontal semicircular $\log$. Equilibrium is obtained with the help of addition of a weight to one of the ends of the board when the board makes an angle $\theta$ with the horizontal. Coefficient of friction between the log and the board is
(a) $\tan \theta$
(b) $\cos \theta$
(c) $\cot \theta$
(d) $\sin \theta$
(Figure can't copy)

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:21

Problem 40

Two similar planes of mass $m$ each having failed engines are being pulled by a stronger plane in air.
At $t=0$, they are travelling at uniform speed producing tension $T_A$ in rope $A$. The stronger plane then accelerates with acceleration $a$. Tension in rope $B$ just after the beginning of acceleration is
(Figure can't copy)
(a) $T_A$
(b) $T_A-m a$
(c) $2 T_A+m a$
(d) $\frac{T_A}{2}+m a$

Ajay Singhal
Ajay Singhal
Numerade Educator
02:14

Problem 41

Velocity of a bullet changes from $u$ to $v$ after passing through a board of thickness $d$. Force of resistance is directly proportional to the velocity. Time of motion of bullet in the board is given by
(a) $\frac{d(u-v)}{u v \log _{\ell} \frac{u}{v}}$
(b) $\frac{d u}{v \log _e \frac{u}{v}}$
(c) $\frac{d v}{u \log _e \frac{u}{v}}$
(d) $\frac{d(v-u)}{u v \log _{\ell} \frac{v}{u}}$

Yuva S
Yuva S
Numerade Educator
05:42

Problem 42

A rocket of mass $m$ is fired vertically upward and after the fuel burning it weighs $m^{\prime}$. Ejection of fuel gas is at a constant rate of $m_0$ per second with a constant velocity of $u_{\text {red }}$ relative to the rocket. Final speed of rocket after the complete burn out of fuel is given by $v=$
(a) $u_m \log _e \frac{m}{m^{\prime}}$
(b) $u_{\text {ret }} \log , \frac{m_0}{m}$
(c) $-u_{\text {ret }} \log _e \frac{m_0}{m^{\prime}}$
(d) $-u_{\text {vel }} \frac{d m}{m}$

Foster Wisusik
Foster Wisusik
Numerade Educator
02:58

Problem 43

A chain of length $l$ is lying in a smooth horizontal tube such that a fraction of its length $h$ hangs freely and the end touches the ground. At a certain moment the other end of chain is set free. The speed of this end of chain when it slips out of the tube is
(Figure can't copy)
(a) $\left[(2 g h) \frac{d l}{d h}\right]^{1 / 2}$
(b) $\sqrt{g h}$
(c) $\sqrt{2 g l}$
(d) $\left(2 g h \log _e \frac{l}{h}\right)^{\frac{1}{2}}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
03:46

Problem 44

A block of mass $M$ with semicircular track of radius $R$ rests on a horizontal smooth surface. A cylinder of radius $r$ slips on the track. If the cylinder is released from rest from top, the distance moved by block when cylinder reaches the bottom of the track is
(a) $R-r$
(b) $\frac{M(R-r)}{M+m}$
(c) $\frac{M}{M+m}(R-r)$
(d) $\frac{M}{M-m} r$
(Figure can't copy)

Subash Charan
Subash Charan
Numerade Educator
01:05

Problem 45

A chain of length $l$ is placed on a smooth spherical surface of radius $r$ with one of its ends fixed at the top of the surface. Length of chain is assumed to be $l<$ $\frac{\pi r}{2}$. Acceleration of each element of chain when upper end is released is
(Figure can't copy)
(a) $\frac{\lg }{r}\left(1-\cos \frac{r}{l}\right)$
(b) $\frac{r g}{l}\left(1-\cos \frac{l}{r}\right)$
(c) $\frac{\lg }{r}\left(1-\sin \frac{l}{r}\right)$
(d) $\frac{r g}{l}\left(1-\sin \frac{l}{r}\right)$

Nidhi Singhi
Nidhi Singhi
Numerade Educator
01:51

Problem 46

A large free mass $M$ and a small mass $m$ are connected to a string such that $m$ moves in horizontal circle. Length of string is $l$ and $\theta$ is the angle this length makes with vertical. The frequency of rotation of mass $m$ so that $M$ remains at rest is
(Figure can't copy)
(a) $2 \pi \sqrt{\frac{m l}{M g}}$
(b) $\frac{1}{2 \pi} \sqrt{\frac{m g}{M l}}$
(c) $\frac{1}{2 \pi} \sqrt{\frac{m l}{M g}}$
(d) $\frac{1}{2 \pi} \sqrt{\frac{M g}{m l}}$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
04:09

Problem 47

Two blocks connected by a massless string slide down an inclined plane having angle of inclination as $37^{\circ}$. The masses of two blocks are $4 \mathrm{~kg}$ and $2 \mathrm{~kg}$ with $\mu$ as 0.75 and 0.25 respectively.
(a) The common acceleration of two masses is 1.3 $\mathrm{ms}^{-2}$ and tension in string is $5.3 \mathrm{~N}$.
(b) Tension in the string is $14.9 \mathrm{~N}$.
(c) Acceleration of the mass is $3 \mathrm{~N}$.
(d) The acceleration of masses is $5.3 \mathrm{~ms}^{-2}$ and tension in the string is $1.3 \mathrm{~N}$.
(Figure can't copy)

Akshaya Rs
Akshaya Rs
Numerade Educator
02:11

Problem 48

Accelerations of the vehicle and mass $m_2$, when pulleys are light and all surfaces are frictionless, are
(Figure can't copy)
(a) cach $\frac{m_2 g}{4 m_1+m_2}$
(b) $\frac{2 m_2 g}{4 m_1+m_2}, \frac{m_2 g}{4 m_1+m_2}$
(c) cach $\frac{2 m_1 g}{4 m_2+m_1}$
(d) $\frac{m_1 g}{4 m_2+m_1}, \frac{2 m_1 g}{4\left(m_2+m_1\right)}$

Ajay Singhal
Ajay Singhal
Numerade Educator
04:03

Problem 49

A block of mass $m$ slides down an inclined right angled trough. If the coefficient of kinetic friction between the block and the trough is $\mu_k$ acceleration of the block down the plane is
(Figure can't copy)
(a) $g\left(\sin \theta-2 \mu_k \cos \theta\right)$
(b) $g\left(\sin \theta+2 \mu_k \cos \theta\right)$
(c) $g\left(\sin \theta+\sqrt{2} \mu_k \cos \theta\right)$
(d) $g\left(\sin \theta-\mu_k \cos \theta\right)$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
10:46

Problem 50

A cylinder of radius $r=1 \mathrm{~m}$ and mass $m=5 \times 10^3 \mathrm{~kg}$ is at rest on the edges of a structure as shown. Distance $a$ is $0.5 \mathrm{~m}$ and $b=\frac{\sqrt{3}}{2} \mathrm{~m}$. Reaction force on edges $A$ and $B$ are
(Figure can't copy)
(a) $24.6 \mathrm{kN}, 24.6 \mathrm{kN}$
(b) $42.6 \mathrm{kN}, 42.6 \mathrm{kN}$
(c) $42.6 \mathrm{kN}, 24.6 \mathrm{kN}$
(d) $52.6 \mathrm{kN}, 5.6 \mathrm{kN}$

Jonathan Ibarra
Jonathan Ibarra
Numerade Educator
01:45

Problem 51

Two blocks $B_1$ and $B_2$ of masses $m_1$ and $m_2$ respectively are connected with the help of a pulley and string as shown. Upper surface of vehicle is smooth but vertical surface is rough.
(Figure can't copy)
Given $a=g / 7$ and $m_1=7.5 m_2$. Coefficient of friction between block $B_2$ and side of vehicle is
(a) 0.4
(b) 0.5
(c) 0.6
(d) 0.3

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
01:11

Problem 52

Sixteen beads in a string are placed on a smooth inclined plane of inclination $\sin ^{-1}(1 / 3)$ such that some of them lie along the incline whereas the rest hang over the top of the plane. If acceleration at first bead is $g / 2$, the arrangement of beads is that
(Figure can't copy)
(a) 12 hang vertically.
(b) 10 lie along inclined plane.
(c) 8 lie along inclined plane.
(d) 10 hang vertically.

Hast Aggarwal
Hast Aggarwal
Numerade Educator
04:05

Problem 53

A mass $M$ is hung with a light inextensible string. Tension in horizontal part of string is
(Figure can't copy)
(a) $\sqrt{3} \mathrm{Mg}$
(b) $\sqrt{2} M g$
(c) $\frac{M g}{\sqrt{3}}$
(d) $\frac{M g}{2}$

Narendra Kumar
Narendra Kumar
Numerade Educator
01:33

Problem 54

A ship of mass $3 \times 10^7 \mathrm{~kg}$ initially at rest is pulled by a force of $5 \times 10^4 \mathrm{~N}$ through a distance of $3 \mathrm{~m}$. Assuming that resistance due to water is negligible, the speed of ship is
(a) $0.2 \mathrm{~ms}^{-1}$
(b) $0.1 \mathrm{~ms}^{-1}$
(c) $1 \mathrm{~ms}^{-1}$
(d) $2 \mathrm{~ms}^{-1}$

Nishant Kumar
Nishant Kumar
Numerade Educator
03:45

Problem 55

A bullet of mass $M$ is fired with a velocity of $50 \mathrm{~ms}^{-1}$ at an angle $\theta$ with the horizontal. At the highest point of trajectory it collides with a bob of mass $3 M$ suspended vertically by a massless string of length $\frac{10}{3} \mathrm{~m}$ and gets embedded into it. After the collision the string moves through an angle $120^{\circ}$, what is the angle of throw $\theta$.
(a) $\cos ^{-1} \frac{2}{5}$
(b) $\cos ^{-1} \frac{3}{5}$
(c) $\cos ^{-1} \frac{4}{5}$
(d) $\cos ^{-1} \frac{1}{5}$

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
01:34

Problem 56

A car is moving in a circular horizontal track of radius $10 \mathrm{~m}$ with a constant speed of $10 \mathrm{~ms}^{-1}$. A plumb bob is suspended from the roof of car by a light rigid rod of length $1 \mathrm{~m}$. The angle made by rod with the track is
(a) zero
(b) $30^{\circ}$
(c) $45^{\circ}$
(d) $60^{\circ}$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:16

Problem 57

A ball weighing $10 \mathrm{~g}$ hits a hard surface vertically with a speed of $5 \mathrm{~ms}^{-1}$ and rebounds with the same speed. The ball remains in contact with the surface for $0.01 \mathrm{~s}$. The average force exerted by the surface on ball is.
(a) $100 \mathrm{~N}$
(b) $10 \mathrm{~N}$
(c) $1 \mathrm{~N}$
(d) $0.1 \mathrm{~N}$

Narayan Hari
Narayan Hari
Numerade Educator
04:37

Problem 58

Tension in rod of length $L$ and mass $M$ at a distance $y$ from $F_1$ when the rod is acted on by two unequal forces $F_1$ and $F_2$ where $\left(F_2<F_1\right)$ at its ends is
(a) $F_1(1-y / L)+F_2(y / L)$
(b) $F_2(1-y / L)+F_1(y / L)$
(c) $F_1(1+y / L)+F_2(y / L)$
(d) $F_2(1+y / L)+F_1(y / L)$

Nishant Kumar
Nishant Kumar
Numerade Educator
01:48

Problem 59

The magnitude of force (in $\mathrm{N}$ ) acting on a body varies with time $t$ (in $\mu \mathrm{s}$ ) as shown. $A B, B C$ and $C D$ are straight line segments. The magnitude of total impulse of force on the body from $t=4 \mu \mathrm{s}$ to $t=16 \mu \mathrm{s}$ is
(Figure can't copy)
(a) $6 \times 10^{-3} \mathrm{Ns}$
(b) $3 \times 10^{-3} \mathrm{Ns}$
(c) $5 \times 10^{-8} \mathrm{Ns}$
(d) $6 \times 10^{-3} \mathrm{Ns}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:51

Problem 60

A smooth semicircular wire track of radius $R$ is fixed in a vertical plane. One end of a massless spring of natural length $3 R / 4$ is attached to the lowest point $O$ of the wire track. A small ring of mass $m$ which can slide on the track is attached to the other end of the spring. The ring is held stationary at point $P$ such that the spring makes an angle $60^{\circ}$ with the vertical. Spring constant $K=m g /$ $R$. The spring force is
(Figure can't copy)
(a) $\frac{m g}{3}$
(b) $m g$
(c) $\frac{m g}{2}$
(d) $\frac{m g}{4}$

Varsha Aggarwal
Varsha Aggarwal
Numerade Educator
02:10

Problem 61

Block $A$ of mass $m$ and block $B$ of mass $2 m$ are placed on a fixed triangular wedge by means of massless, inextensible string and a frictionless pulley as shown. The wedge is inclined at $45^{\circ}$ to horizontal on both sides. The coefficient of friction between block $A$ and wedge is $2 / 3$ and that between block $B$ and wedge is $1 / 3$. If system of $A$ and $B$ is released from rest then acceleration of $A$ is
(Figure can't copy)
(a) zero
(b) $1 \mathrm{~ms}^{-2}$
(c) $2 \mathrm{~ms}^{-2}$
(d) $3 \mathrm{~ms}^{-2}$

Surendra Kumar
Surendra Kumar
Numerade Educator
02:24

Problem 62

A large heavy box is sliding without friction down a smooth plane of inclination $\theta$. From a point $P$ on the bottom of the box, a particle is projected inside the box. The initial speed of particle with respect to the box is $u$ and the direction of projection makes an angle $\alpha$ with the bottom as shown. Find the distance along the bottom of box between the point of projection $P$ and point $Q$ where the particle lands. (Assume that the particle does not hit any other surface of the box. Neglect air resistance)
(Figure can't copy)
(a) $\frac{u^2 \sin 2 \alpha}{g}$
(b) $\frac{u^2 \sin ^2 \alpha}{2 g \cos \theta}$
(c) $\frac{u^2 \sin 2 \alpha}{g \cos \theta}$
(d) $\frac{u^2 \sin \alpha}{g}$

Mahendra K
Mahendra K
Numerade Educator
01:24

Problem 63

A spring of force constant $K$ is cut into two pieces such that one piece is double the length of the other. Then the long piece will have a foree constant of
(a) $2 / 3 K$
(b) $3 / 2 \mathrm{~K}$
(c) $3 K$
(c) $6 K$

Ajay Singhal
Ajay Singhal
Numerade Educator
00:35

Problem 64

A cubical block of side $L$ rests on a rough horizontal surface with coefficient of friction $\mu$. A horizontal force $F$ is applied on the block as shown. If the coefficient of friction is sufficiently high so that the block does not slide before toppling, the minimum force required to topple the block is
(Figure can't copy)
(a) infinitesimal
(b) $m g / 4$
(c) $m g / 2$
(d) $m g(1-\mu)$

Hunza Gilgit
Hunza Gilgit
Numerade Educator
06:00

Problem 65

An insect crawls up a hemispherical surface very slowly. The coefficient of friction between the surface and the insect is $1 / 3$. If the line joining the centre of the hemispherical surface to the insect makes an angle $\alpha$ with the vertical, the maximum possible value of $\alpha$ is given by
(Figure can't copy)
(a) $\cot \alpha=3$
(b) $\tan \alpha=3$
(c) $\sec \alpha=3$
(d) $\operatorname{cosec} \alpha=3$

Ravindra Yadav
Ravindra Yadav
Numerade Educator
03:34

Problem 66

A string of negligible mass going over a clamped pulley of mass $m$ supports a block of mass $M$ as shown in the figure. The force on the pulley by the clamp is given by
(Figure can't copy)
(a) $\sqrt{2} M g$
(b) $\sqrt{2} m g$
(c) $g \sqrt{(M+m)^2+m^2}$
(d) $g \sqrt{(M+m)^2+M^2}$

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
04:29

Problem 67

The pulleys and string shown in figure are smooth and of negligible mass. For the system to remain in equilibrium, the angle $\theta$ should be
(Figure can't copy)
(a) $0^{\circ}$
(b) $30^{\circ}$
(c) $45^{\circ}$
(d) $60^{\circ}$

Ravindra Yadav
Ravindra Yadav
Numerade Educator
02:25

Problem 68

An ideal spring with spring constant $k$ is hung from the ceiling and a block of mass $M$ is attached to its lower end. The mass is released with the spring initially unstretched. Then the maximum extension in the spring is
(a) $4 \mathrm{Mg} / \mathrm{k}$
(b) $2 \mathrm{Mg} / \mathrm{k}$
(c) $M g / k$
(d) $M g / 2 k$

Yuva S
Yuva S
Numerade Educator
05:03

Problem 69

A force $F_1$ acts on a particle so as to accelerate it from rest to a velocity $v$. The force $F_1$ is then replaced by $F_2$ which decelerates it to rest.
(a) $F_1$ must be equal to $F_2$
(b) $F_1$ may be equal to $F_2$
(c) $F_1$ must be unequal to $F_2$
(d) none of these

Vishal Gupta
Vishal Gupta
Numerade Educator
01:12

Problem 70

Two objects $A$ and $B$ are thrown upward simultaneously with the same speed. The mass of $A$ is greater than the mass of $B$. Suppose the air exerts a constant and equal force of resistance on the two bodies
(a) the two bodies will reach the same height.
(b) $A$ will go higher than $B$.
(c) $B$ will go higher than $A$.
(d) any of the above three may happen depending on the speed with which the objects are thrown.

Satpal Satpal
Satpal Satpal
Numerade Educator
01:22

Problem 71

A smooth wedge $A$ is fitted in a chamber hanging from a fixed ceiling near the earth's surface. A block $B$ placed at the top of the wedge takes a time $T$ to slide down the length of the wedge. If the block is placed at the top of the wedge and the cable supporting the chamber is broken at the same instant, the block will
(a) take a time longer than $T$ to slide down the wedge.
(b) take a time shorter than $\mathrm{T}$ to slide down the wedge.
(c) remain at the top of the wedge.
(d) jump off the wedge.

Ajay Singhal
Ajay Singhal
Numerade Educator
02:01

Problem 72

In an imaginary atmosphere, the air exerts a small force $F$ on any particle in the direction of the particle's motion.
A particle of mass $m$ projected upward takes a time $t_1$ in reaching the maximum height and $t_2$ in the return journey to the original point. Then
(a) $t_1<t_2$
(b) $t_1>t_2$
(c) $t_1=t_2$
(d) the relation between $t_1$ and $t_2$ depends on the mass of the particle

Mahendra K
Mahendra K
Numerade Educator
01:41

Problem 73

A person standing on the floor of an elevator drops a coin. The coin reaches the floor of the elevator in a time $t_1$ if the elevator is stationary and in time $t_2$ if it is moving uniformly. Then
(a) $t_1=t_2$
(b) $t_1<t_2$
(c) $t_1>t_2$
(d) $t_1<t_2$ or $t_1>t_2$ depending on whether the lift is going up or down.

Narayan Hari
Narayan Hari
Numerade Educator
01:44

Problem 74

A free ${ }^{28} U$ nucleus kept in a train emits an alpha particle When the train is stationary, a nucleus decays and a passenger measures that the separation between the alpha particle and the recoiling nucleus becomes $x$ at time $t$ after the decay. If the decay takes place while the train is moving at a uniform velocity $v$, the distance between the alpha particle and the recoiling nucleus at a time $t$ after the decay as measured by the passenger is
(a) $x+v t$
(b) $x-v t$
(c) $x$
(d) depends on the direction of the train

Akshaya Rs
Akshaya Rs
Numerade Educator
01:08

Problem 75

Figure shows a heavy block kept on a frictionless surface and being pulled by two ropes of equal mass $m$. At $t=0$, the force on the left rope is withdrawn but the force on the right end continues to act. Let $F_1$ and $F_2$ be the magnitudes of the forces by the right rope and the left rope on the block respectively.
(Figure can't copy)
(a) $F_1=F_3=F$ for $t<0$
(b) $F_1=F_2=F+m g$ for $t<0$
(c) $F_1=F_2 F_2=F$ for $t>0$
(d) $F_1<F, \mathrm{~F}_2^2=F$ for $t>0$.

Ajay Singhal
Ajay Singhal
Numerade Educator
02:02

Problem 76

A monkey of mass $20 \mathrm{~kg}$ is holding a vertical rope. The rope can break when a mass of $25 \mathrm{~kg}$ is suspended from it. What is the maximum acceleration with which the monkey can climb up along the rope?
(a) $7 \mathrm{~ms}^{-2}$
(b) $10 \mathrm{~ms}^{-2}$
(c) $5 \mathrm{~ms}^2$
(d) $2.5 \mathrm{~ms}^5$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:46

Problem 77

A force of 5 Newton acts on a body of weight 9.8 Newton. What is the acceleration produced in $\mathrm{ms}^{-2}$ ?
(a) 0.51
(b) 1.46
(c) 49.00
(d) 5.00

Vysakh M
Vysakh M
Numerade Educator
01:36

Problem 78

A body of mass $m$ is released from the top of a rough inclined plane of length $l$. If the frictional force is $\mathrm{f}$ then the velocity of the body of the bottom in $\mathrm{ms}^{-1}$ will be
(a) $\sqrt{\frac{2}{m}(m g h-l)}$
(b) $2 g h-f l l$
(c) $\sqrt{\frac{2}{m}} g h$
(d) zero

Kristela Garcia
Kristela Garcia
Numerade Educator
05:50

Problem 79

A block of mass $2 \mathrm{~kg}$ is lying on a floor. The coefficient of static friction is 0.54 . What will be the value of frictional force if the force is $2.8 \mathrm{~N}$ and $\mathrm{g}=10 \mathrm{~ms}^{-2}$
(a) zero
(b) $2 \mathrm{~N}$
(c) $2.8 \mathrm{~N}$
(d) $8 \mathrm{~N}$

Ravindra Yadav
Ravindra Yadav
Numerade Educator
01:19

Problem 80

A cube weighing $10 \mathrm{~N}$ is lying on a rough inclined plane of slope 3 in 5 . The coefficient of friction between the plane and the cube is 0.6 . The force necessary to move the cube up the plane will be
(a) $6.4 \mathrm{~N}$
(b) $10.8 \mathrm{~N}$
(c) $21.6 \mathrm{~N}$
(d) $108 \mathrm{~N}$

Narayan Hari
Narayan Hari
Numerade Educator
01:28

Problem 81

A block of metal is lying on the floor of a bus. The maximum acceleratin which can be given to the bus so that the block may remain at rest, will be
(a) $\mu \mathrm{g}^2$
(b) $\mu^2 g$
(c) $\mu g$
(d) $\mu / g$

Suman Saurav Thakur
Suman Saurav Thakur
Numerade Educator
02:22

Problem 82

A body of weight $w$ is lying at rest on a rough horizontal surface. If the angle of friction is $\theta$, then the minimum force required to move the body along the surface will be
(a) $w \cos \theta$
(b) $w \tan \theta$
(c) $w \sin \theta$
(d) $w \cot \theta$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
02:59

Problem 83

A block of mass $0.5 \mathrm{~kg}$. rests against a wall exerting a horizontal force of $10 \mathrm{~N}$ on the wall If the coefficient of friction between the wall and the block is 0.5 then the frictional force acting on the block will be
(a) $49.9 \mathrm{~N}$
(b) $9.8 \mathrm{~N}$
(c) $4.90 \mathrm{~N}$
(d) $0.49 \mathrm{~N}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:45

Problem 84

A rope of length $l$ is pulled with a constant force $f . T$ is the tension in the rope at a point distant $x$ from the end where the force is applied. Then $T$ is
(a) $f(l-x) / l$
(b) $f l /(l-x)$
(c) $\frac{(f-x)}{l-x}$
(d) $\frac{f l}{x}$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:03

Problem 85

Two masses $m_1$ and $m_2$ are attached to a string which pass over a frictionless fixed pully. Given that $m_1=10$ $\mathrm{kg}$ and $m_2=6 \mathrm{~kg}$ and $\mathrm{g}=10 \mathrm{~ms}^{-2}$. What is the acceleration of the masses?
(a) $2.5 \mathrm{~ms}^{-2}$
(b) $5 \mathrm{~ms}^{-2}$
(c) $20 \mathrm{~ms}^2$
(d) $40 \mathrm{~ms}^{-2}$

Raj Bala
Raj Bala
Numerade Educator
01:57

Problem 86

A block is lying on the table. What is the angle between the action of the block on the table and the reaction of the table on the block?
(a) $180^{\circ}$
(b) $90^{\circ}$
(c) $45^{\circ}$
(d) $0^{\circ}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:08

Problem 87

A parachutist of weight $w$ strikes the ground with his legs fixed and comes to rest with an upward acceleration of magnitude $3 \mathrm{~kg}$. Force exerted on him by ground during landing is
(a) $4 w$
(b) $3 w$
(c) $2 w$
(d) $w$

Ajay Singhal
Ajay Singhal
Numerade Educator
01:08

Problem 88

The force that prevents the relative motion between the layers of a liquid is called
(a) static friction
(b) sliding friction
(c) contact friction
(d) none of these

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:06

Problem 89

Gravels are dropped on a conveyer belt at the rate of 0.5 $\mathrm{kgs}^{-1}$. The extra force required in newtons to keep the belt moving at $2 \mathrm{~ms}^{-1}$ is
(a) 0.5
(b) 1
(c) 2
(d) 4

Ajay Singhal
Ajay Singhal
Numerade Educator
01:11

Problem 90

Starting from rest, a body slides down a $45^{\circ}$ inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of friction between the body and the inclined plane is
(a) 0.25
(b) 0.33
(c) 0.75
(d) 0.80

Ajay Singhal
Ajay Singhal
Numerade Educator
01:53

Problem 91

When we walk once, we should take small steps to avoid slipping. This is because smaller steps ensure
(a) larger friction
(b) smaller friction
(c) larger normal force
(d) smaller normal force

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
02:08

Problem 92

A chain of length $L$ and mass $m$ is allowed to fall on a table such that the part falling on the table comes to rest instantaneously. The force acting on the table when I part of it has lied on the table is
(a) $\frac{3 m / g}{L}$
(b) $\frac{2 m / g}{L}$
(c) $\frac{m l g}{L}$
(d) $\frac{3 m l g}{2 L}$

Mahendra K
Mahendra K
Numerade Educator
03:55

Problem 93

Two balls of mass $1 \mathrm{~kg}$ and $2 \mathrm{~kg}$ respectively are connected to the two ends of the spring. The two balls are pressed together and placed on a smooth table. When released, the lighter ball moves with an acceleration of $2 \mathrm{~ms}^{-2}$. The acceleration of the heavier ball will be
(a) $0.2 \mathrm{~ms}^{-2}$
(b) $1 \mathrm{~ms}^{-2}$
(c) $2 \mathrm{~ms}^{-2}$
(d) $4 \mathrm{~ms}^{-2}$

Karan Soni
Karan Soni
Numerade Educator
01:35

Problem 94

A fireman wants to slide down a rope. The breaking load for the rope is $3 / 4^{\mathrm{t}}$ of the weight of the man. With what minimum acceleration should the fireman slide down? Acceleration due to gravity is $g$.
(a) zero
(b) $\frac{g}{4}$
(c) $\frac{3 g}{4}$
(d) $\frac{g}{2}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:52

Problem 95

A rain drop of mass $0.1 \mathrm{~g}$ is falling with uniform speed of $10 \mathrm{~cm}^{-1}$. What is the net weight of the drop?
(a) $10^{-2} \mathrm{~N}$
(b) $10^{-3} \mathrm{~N}$
(c) $2 \times 10^{-3} \mathrm{~N}$
(d) zero

Vysakh M
Vysakh M
Numerade Educator
02:26

Problem 96

A heavy unifrom bar is being carried by two men on their shoulders. The weight of the bar is $w$. If one man lets it fall from the end carried by him, what will be the weight experienced by the other?
(a) none of these
(b) $w / 4$
(c) $w / 2$
(d) $w$

Hunza Gilgit
Hunza Gilgit
Numerade Educator
02:35

Problem 97

The coefficient of friction of an inclined plane is $1 / \sqrt{3}$. If it is inclined at angle $30^{\circ}$ with the horizontal, what will be the downward acceleration of the block placed on the inclined plane?
(a) 0
(b) $\sqrt{2} \mathrm{~ms}^{-2}$
(c) $\sqrt{3} \mathrm{~ms}^{-2}$
(d) $3 \mathrm{~ms}^{-2}$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
03:29

Problem 98

A body is projected upwards with a kinetic energy of $100 \mathrm{~J}$. Taking the friction of air into account, when it retums on earth, its kinetic energy will be
(a) more than $100 \mathrm{~J}$
(b) less than $100 \mathrm{~J}$
(c) $100 \mathrm{~J}$
(d) none of these

Narendra Kumar
Narendra Kumar
Numerade Educator
01:08

Problem 99

Which of the following is a self adjusted force?
(a) Sliding friction
(b) Static friction
(c) Limiting friction
(d) Dynamic friction

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
02:33

Problem 100

A body is placed over an inclined plane of angle $\pi-\theta$. The angle between normal reaction and the weight of the body is
(a) equal to the angle of friction
(b) more than $\theta$
(c) less than $\theta$
(d) $\theta$

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
01:19

Problem 101

The frictional force due to air on a body of mass $0.25 \mathrm{~kg}$ falling with an acceleration of $9.2 \mathrm{~ms}^{-1}$ will be
(a) $0.15 \mathrm{~N}$
(b) $1.5 \mathrm{~N}$
(c) $15 \mathrm{~N}$
(d) zero

Ajay Singhal
Ajay Singhal
Numerade Educator
00:37

Problem 102

If a rough surface is polished beyond a certain limit than the magnitude of frictional force will
(a) nothing can be said
(b) some time increases and some time decreases
(c) increase
(d) decrease

Saman Zulfiqar
Saman Zulfiqar
Numerade Educator
01:16

Problem 103

A car is moving on a straight horizontal road with a speed of $72 \mathrm{kmh}-1$. If the coefficient of static friction between the tyre of the car and the road is 0.5 , then the minimum distance, within which the car can be stopped will be
(a) $72 \mathrm{~m}$
(b) $40 \mathrm{~m}$
(c) $30 \mathrm{~m}$
(d) $20 \mathrm{~m}$

Narayan Hari
Narayan Hari
Numerade Educator
01:12

Problem 104

When we kick a stone, we get hurt. Due to which one of the following properties does it happens?
(a) Velocity
(b) Momentum
(c) Inertia
(d) Reaction

Dheeraj Sharma
Dheeraj Sharma
Numerade Educator
02:45

Problem 105

A cricket player catches a ball of mass $100 \mathrm{~g}$ and moving with a velocity of $25 \mathrm{~ms}^{-1}$. If the ball is caught $0.1 \mathrm{~s}$, the force of the blow exerted on the hand of the player is
(a) $4 \mathrm{~N}$
(b) $40 \mathrm{~N}$
(c) $25 \mathrm{~N}$
(d) $250 \mathrm{~N}$

Vysakh M
Vysakh M
Numerade Educator