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# College Physics 2017

## Educators

BS
+ 1 more educators

### Problem 1

Calculate the magnitude of the linear momentum for the following cases: (a) a proton with mass equal to $1.67 \times$ $10^{-27} {kg},$ moving with a speed of $5.00 \times 10^{6} {m} / {s} ;({b})$ a 15.0 ${-g}$ bullet moving with a speed of $300 {m} / {s} ;({c})$ a 75.0 -kg sprinter running with a speed of $10.0 {m} / {s} ;$ (d) the Earth (mass $=$ $5.98 \times 10^{24} {kg}$ ) moving with an orbital speed equal to $2.98 \times$ $10^{4} {m} / {s} .$

Salamat A.

### Problem 2

A high-speed photograph of a club hitting a golf ball is shown in Figure 6.3. The club was in contact with a ball, initially at rest, for about 0.0020 s. If the ball has a mass of 55 ${g}$ and leaves the head of the club with a speed of $2,0 \times 10^{2} {ft} / {s},$ find the average force exerted on the ball by the club.

Averell H.
Carnegie Mellon University

### Problem 3

A pitcher claims he can throw a 0.145-kg baseball with as much momentum as a 3.00-g bullet moving with a speed of $1.50 \times 10^{3} {m} / {s}$ . (a) What must the baseball's speed be if the
pitcher's claim is valid? (b) Which has greater kinetic energy, the ball or the bullet?

Salamat A.

### Problem 4

A 0.280-kg volleyball approaches a player horizontally with a speed of 15.0 m/s. The player strikes the ball with her fist and causes the ball to move in the opposite direction with a speed of 22.0 m/s. (a) What impulse is delivered to the ball by the player? (b) If the player’s fist is in contact with the ball for
0.060 0 s, find the magnitude of the average force exerted on the player’s fist.

Averell H.
Carnegie Mellon University

### Problem 5

Q C Drops of rain fall perpendicular to the roof of a parked car during a rainstorm. The drops strike the roof with a speed of 12 m/s, and the mass of rain per second striking the roof is 0.035 kg/s. (a) Assuming the drops come to rest after striking the roof, find the average force exerted by the rain on the
roof. (b) If hailstones having the same mass as the raindrops fall on the roof at the same rate and with the same speed, how would the average force on the roof compare to that found in part (a)?

Salamat A.

### Problem 6

Show that the kinetic energy of a particle of mass m is related to the magnitude of the momentum p of that particle by $K E=p^{2} / 2 m .$ (Note: This expression is invalid for particles traveling at speeds near that of light.)

Averell H.
Carnegie Mellon University

### Problem 7

An object has a kinetic energy of 275 J and a momentum of magnitude 25.0 kg ? m/s. Find the (a) speed and (b) mass of the object.

Salamat A.

### Problem 8

An estimated force vs. time curve for a baseball struck by a bat is shown in Figure P6.8. From this curve, deter- mine (a) the impulse delivered to the ball and (b) the average force exerted on the ball.

Averell H.
Carnegie Mellon University

### Problem 9

A soccer player takes a corner kick, lofting a stationary ball 35.0° above the horizon at 22.5 m/s. If the soccer ball has
a mass of 0.425 kg and the player’s foot is in contact with it for $5.00 \times 10^{-2} {s}$ , find (a) the $x-$ and $y$ -components of the soccer ball's change in momentum and (b) the magnitude of the average force exerted by the player's foot on the ball.

Salamat A.

### Problem 10

A man claims he can safely hold on to a 12.0-kg child in a head-on collision with a relative speed of 120-mi/h lasting for 0.10 s as long as he has his seat belt on. (a) Find the magnitude of the average force needed to hold onto the child. (b) Based on the result to part (a), is the man’s claim valid? (c) What does the answer to this problem say about laws requiring the use of proper safety devices such as seat belts
and special toddler seats?

Averell H.
Carnegie Mellon University

### Problem 11

A ball of mass 0.150 kg is dropped from rest from a height of 1.25 m. It rebounds from the floor to reach a height of 0.960 m. What impulse was given to the ball by the floor?

Salamat A.

### Problem 12

A tennis player receives a shot with the ball $(0.0600 {kg})$ traveling horizontally at 50.0 ${m} / {s}$ and returns the shot with the ball traveling horizontally at 40.0 ${m} / {s}$ in the opposite direction. (a) What is the impulse delivered to the ball by the racket? (b) What work does the racket do on the ball?

Averell H.
Carnegie Mellon University

### Problem 13

A car is stopped for a traffic signal. When the light turns green, the car accelerates, increasing its speed from 0 to 5.20 m/s in 0.832 s. What are the magnitudes of (a) the linear impulse and (b) the average total force experienced by a 70.0-kg passenger in the car during the time the car accelerates?

Salamat A.

### Problem 14

A 65.0-kg basketball player jumps vertically and leaves the floor with a velocity of 1.80 m/s upward. (a) What impulse does the player experience? (b) What force does the floor exert on the player before the jump? (c) What is the total average force exerted by the floor on the player if the player is in
contact with the floor for 0.450 s during the jump?

Averell H.
Carnegie Mellon University

### Problem 15

The force shown in the force vs. time diagram in Figure P6.15 acts on a 1.5-kg object. Find (a) the impulse of the force, (b) the final velocity of the object if it is initially at rest, and (c) the final velocity of the object if it is initially moving along the x - axis with a velocity of 22.0 m/s.

Salamat A.

### Problem 16

A force of magnitude $F_{x}$ acting in the $x$ -direction on a 2.00 -kg particle varies in time as shown in Figure P6.16. Find (a) the impulse of the force, (b) the final velocity of the particle if it is initially at rest, and (c) the final velocity of the particle if it is initially moving along the x - axis with a velocity of 22.00 m/s.

Averell H.
Carnegie Mellon University

### Problem 17

The forces shown in the force vs. time diagram in Figure P6.17 act on a 1.5 - kg particle. Find (a) the impulse for the interval from t 5 0 to t 5 3.0 s and (b) the impulse for the interval from t 5 0 to t 5 5.0 s. If the forces act on a 1.5 - kg particle that is initially at rest, find the particle’s speed (c) at t 5 3.0 s and (d) at t 5 5.0 s.

Salamat A.

### Problem 18

V A 3.00-kg steel ball strikes a massive wall at 10.0 m/s at an angle of u 5 60.0° with the plane of the wall. It bounces off the wall with the same speed and angle (Fig. P6.18). If the ball is in contact with the wall for 0.200 s, what is the average force exerted by the wall on the ball?

Averell H.
Carnegie Mellon University

### Problem 19

T The front 1.20 m of a 1 400-kg car is designed as a “crumple zone” that collapses to absorb the shock of a collision. If a car traveling 25.0 m/s stops uniformly in 1.20 m, (a) how long does the collision last, (b) what is the magnitude of the average force on the car, and (c) what is the acceleration of the car?Express the acceleration as a multiple of the acceleration of gravity.

Salamat A.

### Problem 20

Q C A pitcher throws a 0.14-kg baseball toward the batter so that it crosses home plate horizontally and has a speed of 42 m/s just before it makes contact with the bat. The batter then hits the ball straight back at the pitcher with a speed of 48 m/s. Assume the ball travels along the same line leaving the bat as it followed before contacting the bat. (a) What is the magnitude of the impulse delivered by the bat to the baseball? (b) If the ball is in contact with the bat for 0.005 0 s, what is the magnitude of the average force exerted by the bat on the ball? (c) How does your answer to part (b) compare to the weight of the ball?

Averell H.
Carnegie Mellon University

### Problem 21

V High-speed stroboscopic photographs show that the head of a $2.00 \times 10^{2}$ -g golf club is traveling at 55.0 $\mathrm{m} / \mathrm{s}$ just before it strikes a 46.0 - g golf ball at rest on a tee. After the collision, the club head travels (in the same direction) at 40.0 m/s. Find the speed of the golf ball just after impact.

Salamat A.

### Problem 22

A rifle with a weight of 30.0 ${N}$ fires a $5.00-{g}$ bullet with a speed of $3.00 \times 10^{2} {m} / {s}$ . (a) Find the recoil speed of the rifle. (b) If ${a} 7.00 \times 10^{2}-{N}$ man holds the rifle firmly against his shoulder, find the recoil speed of the man and rifle.

Averell H.
Carnegie Mellon University

### Problem 23

A 45.0 - kg girl is standing on a 150. - kg plank. The plank, origi- nally at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.50 m/s to the right relative to the plank.
(a) What is her velocity relative to the surface of the ice? (b) What is the velocity of the plank relative to the surface of the ice?

Salamat A.

### Problem 24

This is a symbolic version of Problem 23. A girl of mass mG is standing on a plank of mass mP. Both are originally at rest on a frozen lake that constitutes a frictionless, flat surface. The girl begins to walk along the plank at a constant velocity vGP to the right relative to the plank. (The subscript GP denotes the girl
relative to plank.) (a) What is the velocity vPI of the plank relative to the surface of the ice? (b) What is the girl’s velocity vGI relative to the ice surface?

Averell H.
Carnegie Mellon University

### Problem 25

Squids are the fastest marine invertebrates, using a powerful set of muscles to take in and then eject water in a form of jet propulsion that can propel them to speeds of over 11.5 m/s. What speed would a stationary 1.50 - kg squid achieve by ejecting 0.100 kg of water (not included in the squid’s mass) at 3.25 m/s?

Salamat A.

### Problem 26

A 75 -kg fisherman in a $125-{kg}$ boat throws a package of mass $m=15 {kg}$ horizontally toward the right with a speed of $v_{i}=$
4.5 ${m} / {s}$ as in Figure ${P} 6.26 .$ Neglecting water resistance, and assuming the boat is at rest before the package is thrown, find the velocity of the boat after the package is thrown.

Averell H.
Carnegie Mellon University

### Problem 27

A 65.0 - kg person throws a 0.045 0 - kg snowball forward with a ground speed of 30.0 m/s. A second person, with a mass of 60.0 kg, catches the snowball. Both people are on skates. The first person is initially moving forward with a speed of 2.50 m/s, and the second person is initially at rest. What are
the velocities of the two people after the snowball is exchanged? Disregard friction between the skates and the ice.

Salamat A.

### Problem 28

Two objects of masses $m_{1}=$ 0.56 ${kg}$ and $m_{2}=0.88 {kg}$ are placed on a horizontal frictionless surface and a compressed spring of force constant k 5 280 N/m is placed between them as in Figure P6.28a. Neglect the mass of the spring. The spring is not attached to either object and is compressed a distance of 9.8 cm. If the objects are released from rest, find the final velocity of each object as shown in Figure P6.28b.

Averell H.
Carnegie Mellon University

### Problem 29

An astronaut in her space suit has a total mass of 87.0 kg, including suit and oxygen tank. Her tether line lose its attachment to her spacecraft while she’s on a spacewalk. Initially at rest with respect to her spacecraft, she throws her 12.0 - kg oxygen tank away from her spacecraft with a speed of 8.00 m/s to propel herself back toward it (Fig. P6.29). (a) Determine the maximum distance she can be from the craft and still return within 2.00 min (the amount of time the air in her helmet remains breathable). (b) Explain in terms of Newton’s laws of motion why this strategy works.

Salamat A.