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  • Vector Mechanics for Engineers: Statics and Dynamics
  • Plane Motion of Rigid Bodies: Forces and Accelerations

Vector Mechanics for Engineers: Statics and Dynamics

Ferdinand P. Beer, E. Russell Johnston, Jr., David F. Mazurek

Chapter 16

Plane Motion of Rigid Bodies: Forces and Accelerations - all with Video Answers

Educators


Section 1

Kinetics of a Rigid Body

Problem 1

A 60 -lb uniform thin panel is placed in a truck with end $A$ resting on a rough horizontal surface and end $B$ supported by a smooth vertical surface. Knowing that the deceleration of the truck is $12 \mathrm{ft} / \mathrm{s}^{2},$ deter mine ( $a$ ) the reactions at ends $A$ and $B$, (b) the minimum required coefficient of static friction at end $A$.

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Problem 2

A 60 -lb uniform thin panel is placed in a truck with end $A$ resting on a rough horizontal surface and end $B$ supported by a smooth vertical surface. Knowing that the panel remains in the position shown, deter mine ( $a$ ) the maximum allowable acceleration of the truck, ( $b$ ) the corresponding minimum required coefficient of static friction at end $A$.

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Problem 3

A loading car is at rest on a track forming an angle of $25^{\circ}$ with the vertical. The gross weight of the car and its load is $5500 \mathrm{lb}$, and it acts at point $G .$ Knowing the tension in the cable connected at $C$ is $3000 \mathrm{lb}$ determine ( $a$ ) the acceleration of the car, ( $b$ ) the reaction at each pair of wheels.

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Problem 4

A 2100 -lb rear-wheel-drive tractor carries a 900 lb load of gravel centered at point $L .$ Knowing that the tractor starts from rest and accelerates forward at $2 \mathrm{ft} / \mathrm{s}^{2},$ determine the reaction at each of the two (a) rear wheels $A$, ( $b$ ) front wheels $B$.

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Problem 5

A uniform rod $B C$ of mass $4 \mathrm{kg}$ is connected to a collar $A$ by a $250-\mathrm{mm}$ cord $A B .$ Neglecting the mass of the collar and cord, deter mine $(a)$ the smallest constant acceleration $\mathbf{a}_{A}$ for which the cord and the rod will lie in a straight line, $(b)$ the corresponding tension in the cord.

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17:30

Problem 6

A $2000-\mathrm{kg}$ truck is being used to lift a $400-\mathrm{kg}$ boulder $B$ that is on a 50 -kg pallet $A$. Knowing the acceleration of the rear-wheel-drive truck is $1 \mathrm{m} / \mathrm{s}^{2},$ determine $(a)$ the reaction at each of the front wheels, (b) the force between the boulder and the pallet.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
06:33

Problem 7

The support bracket shown is used to transport a cylindrical can from one elevation to another. Knowing that $\mu_{s}=0.25$ between the can and the bracket, determine ( $a$ ) the magnitude of the upward acceleration a for which the can will slide on the bracket, ( $b$ ) the smallest ratio $h / d$ for which the can will tip before it slides.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 8

A load of lumber weighing $W=25 \mathrm{kN}$ is being raised by a crane. The weight of the boom $A B C$ is $3 \mathrm{kN}$ and the combined weight of the truck and driver is $50 \mathrm{kN}$ as shown. Determine the maximum vertical acceleration of the lumber so that the crane does not tip over.

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05:49

Problem 9

A $20-\mathrm{kg}$ cabinet is mounted on casters that allow it to move freely $(\mu=0)$ on the floor. If a 100 -N force is applied as shown, determine (a) the acceleration of the cabinet, ( $b$ ) the range of values of $h$ for which the cabinet will not tip.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
07:03

Problem 10

Solve Prob. 16.9 , assuming that the casters are locked and slide on the rough floor $\left(\mu_{k}=0.25\right)$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 11

A completely filled barrel and its contents have a combined mass of $90 \mathrm{kg}$ and a center of mass at $G .$ A cylinder $C$ with a mass of $200 \mathrm{kg}$ is connected to the barrel as shown. Knowing $\mu_{s}=0.40$ and $\mu_{k}=0.35$ determine the maximum height $h$ so the barrel will not tip.

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09:04

Problem 12

A $40-\mathrm{kg}$ vase has a 200 -mm-diameter base and is being moved using a 100 -kg utility cart as shown. The cart moves freely $(\mu=0)$ on the ground. Knowing the coefficient of static friction between the vase and the cart is $\mu_{s}=0.4,$ determine the maximum force $\mathbf{F}$ that can be applied if the vase is not to slide or tip.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
08:07

Problem 13

The retractable shelf shown is supported by two identical linkage-and spring systems; only one of the systems is shown. A 20 -kg machine is placed on the shelf so that half of its weight is supported by the system shown. If the springs are removed and the system is released from rest, determine ( $a$ ) the acceleration of the machine, ( $b$ ) the tension in link $A B$. Neglect the weight of the shelf and links.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
06:44

Problem 14

Bars $A B$ and $B E$, each with a mass of $4 \mathrm{kg}$, are welded together and are pin-connected to two links $A C$ and $B D$. Knowing that the assembly is released from rest in the position shown and neglecting the masses of the links, determine ( $a$ ) the acceleration of the assembly, ( $b$ ) the forces in the links.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
03:09

Problem 15

At the instant shown, the tensions in the vertical ropes $A B$ and $D E$ are $300 \mathrm{N}$ and $200 \mathrm{N},$ respectively. Knowing that the mass of the uniform bar $B E$ is 5 kg, determine, at this instant, $(a)$ the force $\mathbf{P},(b)$ the magnitude of the angular velocity of each rope, $(c)$ the angular acceleration of each rope.

Narayan Hari
Narayan Hari
Numerade Educator
08:01

Problem 16

Three bars, each of mass $3 \mathrm{kg}$, are welded together and pin-connected to two links $B E$ and $C F$. Neglecting the weight of the links, determine the force in each link immediately after the system is released from rest.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
14:43

Problem 17

Members $A C E$ and $D C B$ are each $600 \mathrm{mm}$ long and are connected by a pin at $C .$ The mass center of the 10 -kg member $A B$ is located at $G$ Determine ( $a$ ) the acceleration of $A B$ immediately after the system has been released from rest in the position shown, $(b)$ the corresponding force exerted by roller $A$ on member $A B$. Neglect the weight of members $A C E$ and $D C B$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 18

A prototype rotating bicycle rack is designed to save space at a train station. The combined weight of platform $B D$ and the bicycle is $40 \mathrm{lb}$ and is centered at $1 \mathrm{ft}$ above the midpoint of the platform. The motor at $A$ causes the support beam $A B$ to have an angular velocity of 10 rpm and zero angular acceleration at $\theta=60^{\circ}$. At this instant, determine the vertical components of the forces exerted on platform $B D$ by the pins at $B$ and $D$.

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Problem 19

The control rod $A C$ is guided by two pins that slide freely in parallel curved slots of radius $200 \mathrm{mm}$. The rod has a mass of $10 \mathrm{kg}$, and its mass center is located at point $G .$ Knowing that for the position shown the vertical component of the velocity of $C$ is $1.25 \mathrm{m} / \mathrm{s}$ upward and the vertical component of the acceleration of $C$ is $5 \mathrm{m} / \mathrm{s}^{2}$ upward, determine the magnitude of the force $\mathbf{P}$.

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Problem 20

The coefficients of friction between the 30 -lb block and the 5 -lb platform $B D$ are $\mu_{s}=0.50$ and $\mu_{k}=0.40 .$ Determine the accelerations of the block and of the platform immediately after wire $A B$ has been cut.

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Problem 21

Draw the shear and bending-moment diagrams for the vertical rod $A B$ of Prob. 16.16.

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Problem 22

Draw the shear and bending-moment diagrams for each of the bars $A B$ and $B E$ of Prob. 16.14.

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08:19

Problem 23

For a rigid body in translation, show that the system of the inertial terms consists of vectors $\left(\Delta m_{i}\right) \overline{\mathbf{a}}$ attached to the various particles of the body, where $\overline{\mathbf{a}}$ is the acceleration of the mass center $G$ of the body. Further show, by computing their sum and the sum of their moments about $G,$ that the inertial terms reduce to a single vector $m \overline{\mathbf{a}}$ attached at $G$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 24

For a rigid body in centroidal rotation, show that the system of the inertial terms consists of vectors $-\left(\Delta m_{i}\right) \omega^{2} \mathbf{r}_{i}^{\prime}$ and $\left(\Delta m_{i}\right)\left(\boldsymbol{\alpha} \times \mathbf{r}_{i}^{\prime}\right)$
attached to the various particles $P_{i}$ of the body, where $\omega$ and $\alpha$ are the angular velocity and angular acceleration of the body, and where $\mathbf{r}_{i}^{\prime}$ denotes the position vector of the particle $P_{i}$ relative to the mass center $G$ of the body. Further show, by computing their sum and the sum of their moments about $G$, that the inertial terms reduce to a couple $\bar{I} \boldsymbol{\alpha}$.

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03:17

Problem 25

It takes 10 min for a 2.4 -Mg flywheel to coast to rest from an angular velocity of 300 rpm. Knowing that the radius of gyration of the flywheel is $1 \mathrm{m}$, determine the average magnitude of the couple due to kinetic friction in the bearing.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 26

The rotor of an electric motor has an angular velocity of 3600 rpm when the load and power are cut off. The 120 -lb rotor, which has a centroidal radius of gyration of 9 in., then coasts to rest. Knowing that kinetic friction results in a couple of magnitude 2.5 lb-ft exerted on the rotor, determine the number of revolutions that the rotor executes before coming to rest.

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Problem 27

The 10 -in. -radius brake drum is attached to a larger flywheel that is not shown. The total mass moment of inertia of the drum and the flywheel about point $C$ is 15 lb-ft.s $^{2}$, and the coefficient of kinetic friction between the drum and the brake shoes is $0.35 .$ When the hydraulic cylinder $F$ is actuated, it exerts a force of 30 lb directed to the right on point $B$ and to the left on point $E .$ Knowing that the angular velocity of the flywheel is 360 rpm counterclockwise when $F$ is actuated, determine the number of revolutions executed by the flywheel before it comes to rest.

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Problem 28

The 10 -in.-radius brake drum is attached to a larger flywheel that is not shown. The coefficient of kinetic friction between the drum and the brake shoe is 0.35 and the angular velocity of the flywheel is 360 rpm counterclockwise when the hydraulic cylinder shown exerts a force of 30 lb directed to the right on point $B$ and to the left on point $E$. Knowing that the drum comes to rest after 100 revolutions, determine the mass moment of inertia about point $C$ of the drum and the flywheel.

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11:51

Problem 29

The 100 -mm-radius brake drum is attached to a flywheel that is not shown. The drum and flywheel together have a mass of $300 \mathrm{kg}$ and a radius of gyration of $600 \mathrm{mm}$. The coefficient of kinetic friction between the brake band and the drum is $0.30 .$ Knowing that a force $\mathbf{P}$ of magnitude $50 \mathrm{N}$ is applied at $A$ when the angular velocity is 180 rpm counterclockwise, determine the time required to stop the flywheel when $a=200 \mathrm{mm}$ and $b=160$ $\mathrm{mm}$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
07:02

Problem 30

The 180 -mm-radius disk is at rest when it is placed in contact with a belt moving at a constant speed. Neglecting the weight of the link $A B$ and knowing that the coefficient of kinetic friction between the disk and the belt is $0.40,$ determine the angular acceleration of the disk while slipping occurs.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
06:11

Problem 31

Solve Prob. 16.30 , assuming that the direction of motion of the belt is reversed.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
09:49

Problem 32

In order to determine the mass moment of inertia of a flywheel of radius $600 \mathrm{mm},$ a 12 -kg block is attached to a wire that is wrapped around the flywheel. The block is released and is observed to fall $3 \mathrm{m}$ in $4.6 \mathrm{s}$. To eliminate bearing friction from the computation, a second block of mass $24 \mathrm{kg}$ is used and is observed to fall $3 \mathrm{m}$ in $3.1 \mathrm{s}$ Assuming that the moment of the couple due to friction remains constant, determine the mass moment of inertia of the flywheel.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 33

The flywheel shown has a radius of 20 in., a weight of $250 \mathrm{lb}$, and a radius of gyration of 15 in. A 30 -lb block $A$ is attached to a wire that is wrapped around the flywheel, and the system is released from rest. Neglecting the effect of friction, determine ( $a$ ) the acceleration of block $A,(b)$ the speed of block $A$ after it has moved $5$ $\mathrm{ft}$.

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12:02

Problem 34

Each of the double pulleys shown has a mass moment of inertia of 15 lb-fts and is initially at rest. The outside radius is 18 in., and the inner radius is 9 in. Determine $(a)$ the angular acceleration of each pulley, ( $b$ ) the angular velocity of each pulley after point $A$ on the cord has moved $10$ $\mathrm{ft}$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 35

Two disks $A$ and $B$, of mass $m_{A}=2 \mathrm{kg}$ and $m_{B}=4 \mathrm{kg}$, are connected by a belt as shown. Assuming no slipping between the belt and the disks, determine the angular acceleration of each disk if a $2.70-\mathrm{N} \cdot \mathrm{m}$ counterclockwise couple $\mathbf{M}$ is applied to disk $A$.

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Problem 36

Two disks $A$ and $B$, of mass $m_{A}=2 \mathrm{kg}$ and $m_{B}=4 \mathrm{kg}$, are connected by a belt as shown. Assuming no slipping between the belt and the disks, determine the angular acceleration of each disk if a $2.70-\mathrm{N} \cdot \mathrm{m}$ counterclockwise couple $\mathbf{M}$ is applied to disk $B$.

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Problem 37

Gear $A$ weighs 1 lb and has a radius of gyration of 1.3 in. $; \operatorname{gear} B$ weighs 6 lb and has a radius of gyration of 3 in.; gear $C$ weighs 9 lb and has a radius of gyration of 4.3 in. Knowing a couple $\mathbf{M}$ of constant magnitude of $40 \mathrm{lb}$ -in. is applied to gear $A,$ determine $(a)$ the angular acceleration of gear $C,(b)$ the tangential force that gear $B$ exerts on gear $C$.

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Problem 38

The 25 -lb double pulley shown is at rest and in equilibrium when a constant 3.5 -lb fr couple $\mathbf{M}$ is applied. Neglecting the effect of friction and knowing that the radius of gyration of the double pulley is 6 in., determine ( $a$ ) the angular acceleration of the double pulley, (b) the tension in each rope.

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Problem 39

A belt of negligible mass passes between cylinders $A$ and $B$ and is pulled to the right with a force $\mathbf{P}$. Cylinders $A$ and $B$ weigh, respectively, 5 and 20 lb. The shaft of cylinder $A$ is free to slide in a vertical slot and the coefficients of friction between the belt and each of the cylinders are $\mu_{s}=0.50$ and $\mu_{k}=0.40 .$ For $P=3.6 \mathrm{lb}$, determine
(a) whether slipping occurs between the belt and either cylinder,
(b) the angular acceleration of each cylinder.

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Problem 40

Solve Prob. 16.39 for $P=2.00$ $\mathrm{lb}$.

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Problem 41

Disk $A$ has a mass of $6 \mathrm{kg}$ and an initial angular velocity of $360 \mathrm{rpm}$ clockwise; disk $B$ has a mass of $3 \mathrm{kg}$ and is initially at rest. The disks are brought together by applying a horizontal force of magnitude $20 \mathrm{N}$ to the axle of disk $A .$ Knowing that $\mu_{k}=0.15$ between the disks and neglecting bearing friction, determine (a) the angular acceleration of each disk, ( $b$ ) the final angular velocity of each disk.

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10:38

Problem 42

Solve Prob. 16.41 , assuming that initially disk $A$ is at rest and disk $B$ has an angular velocity of 360 rpm clockwise.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 43

Disk $A$ has a mass $m_{A}=4 \mathrm{kg},$ a radius $r_{A}=300 \mathrm{mm},$ and an initial angular velocity $\omega_{0}=300$ rpm clockwise. Disk $B$ has a mass $m_{B}=1.6 \mathrm{kg}$ a radius $r_{B}=180 \mathrm{mm},$ and is at rest when it is brought into contact with disk $A$. Knowing that $\mu_{k}=0.35$ between the disks and neglecting bearing friction, determine ( $a$ ) the angular acceleration of each disk,
(b) the reaction at the support $C$.

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13:09

Problem 44

Disk $B$ is at rest when it is brought into contact with disk $A$, which has an initial angular velocity $\boldsymbol{\omega}_{0} .$ ( $a$ ) Show that the final angular velocities of the disks are independent of the coefficient of friction $\mu_{k}$ between the disks as long as $\mu_{k} \neq 0 .$ ( $b$ ) Express the final angular velocity of disk $A$ in terms of $\omega_{0}$ and the ratio of the masses of the two disks, $m_{A} / m_{B}$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 45

Cylinder $A$ has an initial angular velocity of 720 rpm clockwise, and cylinders $B$ and $C$ are initially at rest. Disks $A$ and $B$ each weigh 5 Ib and have radius $r=4$ in. Disk $C$ weighs 20 lb and has a radius of 8 in. The disks are brought together when $C$ is placed gently onto $A$ and $B .$ Knowing that $\mu_{k}=0.25$ between $A$ and $C$ and no slipping occurs between $B$ and $C,$ determine $(a)$ the angular acceleration of each disk, ( $b$ ) the final angular velocity of each disk.

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06:16

Problem 46

Show that the system of the inertial terms for a rigid body in plane motion reduces to a single vector, and express the distance from the mass center $G$ of the body to the line of action of this vector in terms of the centroidal radius of gyration $\bar{k}$ of the body, the magnitude $\bar{a}$ of the acceleration of $G,$ and the angular acceleration $\alpha$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 47

For a rigid body in plane motion, show that the system of the inertial terms consists of vectors $\left(\Delta m_{i}\right) \overline{\mathbf{a}},-\left(\Delta m_{i}\right) \omega^{2} \mathbf{r}_{i}^{\prime},$ and $\left(\Delta m_{i}\right)\left(\boldsymbol{\alpha} \times \mathbf{r}_{i}^{\prime}\right)$
attached to the various particles $P_{i}$ of the body, where $\overline{\mathrm{a}}$ is the acceleration of the mass center $G$ of the body, $\omega$ is the angular velocity of the body, $\alpha$ is its angular acceleration, and $\mathbf{r}_{i}^{\prime}$ denotes the position vector of the particle $P_{i}$ relative to $G$. Further show, by computing their sum and the sum of their moments about $G$, that the inertial terms reduce to a vector $m \overline{\mathbf{a}}$ attached at $G$ and a couple $\bar{I} \alpha$.

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Problem 48

A uniform slender rod $A B$ rests on a frictionless horizontal surface, and a force $\mathbf{P}$ of magnitude 0.75 lb is applied at $A$ in a direction perpendicular to the rod. Knowing that the rod weighs $2 \mathrm{lb}$ determine ( $a$ ) the acceleration of point $A$, ( $b$ ) the acceleration of point $B,(c)$ the location of the point on the bar that has zero acceleration.

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Problem 49

$(a)$ In Prob. $16.48,$ determine the point of the rod $A B$ at which the force $\mathbf{P}$ should be applied if the acceleration of point $B$ is to be zero. (b) Knowing that $P=0.75$ lb, determine the corresponding acceleration of point $A$.

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05:22

Problem 50

A force $\mathbf{P}$ with a magnitude of $3 \mathrm{N}$ is applied to a tape wrapped around the body indicated. Knowing that the body rests on a frictionless horizontal surface, determine the acceleration of $(a)$ point $A,(b)$ point $B$.
A thin hoop of mass $2.4 \mathrm{kg}$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:12

Problem 51

A force $\mathbf{P}$ with a magnitude of $3 \mathrm{N}$ is applied to a tape wrapped around the body indicated. Knowing that the body rests on a frictionless horizontal surface, determine the acceleration of $(a)$ point $A,(b)$ point $B$.
A uniform disk of mass $2.4$ $\mathrm{kg}$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
10:00

Problem 52

A 250 -lb satellite has a radius of gyration of 24 in. with respect to the $y$ axis and is symmetrical with respect to the $z x$ plane. Its orientation is changed by firing four small rockets $-A, B, C,$ and $D-$ each of which produces a 4 -lb thrust $\mathbf{T}$ directed as shown. Determine the angular acceleration of the satellite and the acceleration of its mass center $G(a)$ when all four rockets are fired, $(b)$ when all rockets except $D$ are fired.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
07:59

Problem 53

A rectangular plate of mass $5 \mathrm{kg}$ is suspended from four vertical wires, and a force $\mathbf{P}$ of magnitude $6 \mathrm{N}$ is applied to corner $C$ as shown. Immediately after $\mathbf{P}$ is applied, determine the acceleration of $(a)$ the midpoint of edge $B C,(b)$ corner $B$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
06:56

Problem 54

A uniform semicircular plate with a mass of $6 \mathrm{kg}$ is suspended from three vertical wires at points $A, B,$ and $C,$ and a force $\mathbf{P}$ with a magnitude of $5 \mathrm{N}$ is applied to point $B$. Immediately after $\mathbf{P}$ is applied, determine the acceleration of $(a)$ the mass center of the plate, $(b)$ point $C$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
08:56

Problem 55

A drum with a 200 -mm radius is attached to a disk with a radius of $r_{A}=150 \mathrm{mm} .$ The disk and drum have a combined mass of $5 \mathrm{kg}$ and a combined radius of gyration of $120 \mathrm{mm}$ and are suspended by two cords. Knowing that $T_{A}=35 \mathrm{N}$ and $T_{B}=25 \mathrm{N}$, determine the accelerations of points $A$ and $B$ on the cords.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
04:44

Problem 56

A drum with a 200 -mm radius is attached to a disk with a radius of $r_{A}=140 \mathrm{mm} .$ The disk and drum have a combined mass of $5 \mathrm{kg}$ and are suspended by two cords. Knowing that the acceleration of point $B$ on the cord is zero, $T_{A}=40 \mathrm{N},$ and $T_{B}=20 \mathrm{N}$, determine the combined radius of gyration of the disk and drum.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
06:49

Problem 57

The 12 -lb uniform disk shown has a radius of $r=3.2$ in. and rotates counterclockwise. Its center $C$ is constrained to move in a slot cut in the vertical member $A B,$ and an 11 -lb horizontal force $\mathbf{P}$ is applied at $B$ to maintain contact at $D$ between the disk and the vertical wall. The disk moves downward under the influence of gravity and the friction at $D$. Knowing that the coefficient of kinetic friction between the disk and the wall is 0.12 and neglecting friction in the vertical slot, determine $(a)$ the angular acceleration of the disk, $(b)$ the acceleration of the center $C$ of the disk.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:17

Problem 58

The steel roll shown has a mass of $1200 \mathrm{kg}$, a centroidal radius of gyration of $150 \mathrm{mm},$ and is lifted by two cables looped around its shaft. Knowing that for each cable $T_{A}=3100 \mathrm{N}$ and $T_{B}=3300 \mathrm{N}$ determine ( $a$ ) the angular acceleration of the roll, ( $b$ ) the acceleration of its mass center.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:43

Problem 59

The steel roll shown has a mass of $1200 \mathrm{kg}$, has a centroidal radius of gyration of $150 \mathrm{mm}$, and is lifted by two cables looped around its shaft. Knowing that at the instant shown the acceleration of the roll is $150 \mathrm{mm} / \mathrm{s}^{2}$ downward and that for each cable $T_{A}=3000 \mathrm{N}$, determine (a) the corresponding tension $T_{B}$ ( $b$ ) the angular acceleration of the roll.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 60

The 400 -lb crate shown is lowered by means of two overhead cranes. Knowing that at the instant shown the deceleration of cable $A$ is $3 \mathrm{ft} / \mathrm{s}^{2}$ and that of cable $B$ is $1 \mathrm{ft} / \mathrm{s}^{2},$ determine the tension in each cable.

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Problem 61

The 400 -lb crate shown is lowered by means of two overhead cranes. Knowing that at the instant shown the deceleration of cable $A$ is $3 \mathrm{ft} / \mathrm{s}^{2}$ and that of cable $B$ is $1 \mathrm{ft} / \mathrm{s}^{2},$ determine the tension in each cable.

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14:42

Problem 62

Two uniform cylinders, each of weight $W=14$ lb and radius $r=5$ in. are connected by a belt as shown. If the system is released from rest, determine ( $a$ ) the angular acceleration of each cylinder, ( $b$ ) the tension in the portion of belt connecting the two cylinders, ( $c$ ) the velocity of the center of the cylinder $A$ after it has moved through 3 ft.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 63

A beam $A B$ with a mass $m$ and of uniform cross-section is suspended from two springs as shown. If spring 2 breaks, determine at that instant ( $a$ ) the angular acceleration of the beam, ( $b$ ) the acceleration of point $A,(c)$ the acceleration of point $B$.

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Problem 64

A beam $A B$ with a mass $m$ and of uniform cross-section is suspended from two springs as shown. If spring 2 breaks, determine at that instant ( $a$ ) the angular acceleration of the beam, ( $b$ ) the acceleration of point $A,(c)$ the acceleration of point $B$.

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View

Problem 65

A uniform slender bar $A B$ with a mass $m$ is suspended from two springs as shown. If spring 2 breaks, determine at that instant $(a)$ the angular acceleration of the bar, ( $b$ ) the acceleration of point $A$, ( $c$ ) the acceleration of point $B$.

BS
Brian Schaefer
Numerade Educator
11:04

Problem 66

A thin plate of the shape indicated and of mass $m$ is suspended from two springs as shown. If spring 2 breaks, determine the acceleration at that instant of $(a)$ point $A,(b)$ point $B$.
A square plate of side $b$

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:16

Problem 67

A thin plate of the shape indicated and of mass $m$ is suspended from two springs as shown. If spring 2 breaks, determine the acceleration at that instant of $(a)$ point $A,(b)$ point $B$.
A thin hoop of diameter $b$

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
11:39

Problem 68

A thin plate of the shape indicated and of mass $m$ is suspended from two springs as shown. If spring 2 breaks, determine the acceleration at that instant of $(a)$ point $A,(b)$ point $B$.
A rectangular plate of height $b$ and width $a$

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
09:31

Problem 69

A sphere of radius $r$ and mass $m$ is projected along a rough horizontal surface with the initial velocities indicated. If the final velocity of the sphere is to be zero, express, in terms of $v_{0}, r,$ and $\mu_{k}$ ( $(a)$ the required magnitude of $\boldsymbol{\omega}_{0},(b)$ the time $t_{1}$ required for the sphere to come to rest, $(c)$ the distance the sphere will move before coming to rest.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
05:55

Problem 70

Solve Prob. 16.69 , assuming that the sphere is replaced by a uniform thin hoop of radius $r$ and mass $m$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

Problem 71

A bowler projects an 8 -in.-diameter ball weighing 12 lb along an alley with a forward velocity $\mathbf{v}_{0}$ of $15 \mathrm{ft} / \mathrm{s}$ and a backspin $\omega_{0}$ of $9 \mathrm{rad} / \mathrm{s}$ Knowing that the coefficient of kinetic friction between the ball and the alley is 0.10 , determine ( $a$ ) the time $t_{1}$ at which the ball will start rolling without sliding, $(b)$ the speed of the ball at time $t_{1},(c)$ the distance the ball will have traveled at time $t_{1}$.

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07:32

Problem 72

Solve Prob. 16.71 , assuming that the bowler projects the ball with the same forward velocity but with a backspin of $18 \mathrm{rad} / \mathrm{s}$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
08:53

Problem 73

A uniform sphere of radius $r$ and mass $m$ is placed with no initial velocity on a belt that moves to the right with a constant velocity $\mathbf{v}_{1}$ Denoting by $\mu_{k}$ the coefficient of kinetic friction between the sphere and the belt, determine ( $a$ ) the time $t_{1}$ at which the sphere will start rolling without sliding, $(b)$ the linear and angular velocities of the sphere at time $t_{1}$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
07:22

Problem 74

A sphere of radius $r$ and mass $m$ has a linear velocity $\mathbf{v}_{0}$ directed to the left and no angular velocity as it is placed on a belt moving to the right with a constant velocity $\mathbf{v}_{1}$. If after first sliding on the belt the sphere is to have no linear velocity relative to the ground as it starts rolling on the belt without sliding, determine in terms of $v_{1}$ and the coefficient of kinetic friction $\mu_{k}$ between the sphere and the belt ( $a$ ) the required value of $v_{0},(b)$ the time $t_{1}$ at which the sphere will start rolling on the belt, ( $c$ ) the distance the sphere will have moved relative to the ground at time $t_{1}$.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator

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