PHYSICS 01
CHAPTER 7 EXERCISES
Name: ALBAN, RONEL D.
Course & Schedule: BS EE/ MH 9:00 – 10:30AM_
Date: 04/13/21
Instructor: PROF. ANTO
Multiple Choice.
Write the letter of the correct answer on the space provided before the number.
C. 1. The final momentum of a moving soccer ball is increased if the
A. force acting on it is increased
B. time of contact is increased
C. velocity is increased
D. impulse is decreased
A. 2. Which has a greater momentum, a large car moving at 30 m/s or a small car moving at
30 m/s?
A. the large car
B. the small car
C. Both cars
D. None of the above
C 3. A hammer falling at the rate of 3.00 m/s from the top of a tower accidentally hits the head of a
man who is passing by. How could the impact force experienced by the man be reduced?
A. decrease the man’s velocity
B. decrease the man’s mass
C. decrease the impact time
D. increase the impact time
B. 4. A boy, whose mass is 50.0 kg, is running very fast at the rate of 5.00 m/s when he jumps onto
a stationary cart with a mass of 3.00 kg. Assuming that the boy and the cart move together,
what
is their common velocity?
A. 3.75 m/s
B. 4. 72 m/s
C. 5.90 m/s
D. 7.35 m/s
C 5. A tennis ball is dropped from a height of 3.50 m onto the floor. If the coefficient of
restitution
between floor and ball is 0.85, how high will the ball bounce?
A. 1.46 m
B. 2.00 m
C. 2.53 m
D. 3.25 m
D 6. Which of the following statements is true for momentum? A. Momentum is a
scalar quantity.
A. The standard unit on momentum in the MKS is the Joule.
B. An object with mass only will have momentum.
C. An object with a velocity has momentum. B 7. Which of the following is true about
impulse? A. Impulse is an example of a force.
B. In a collision, the net impulse experienced by an object is equal to its momentum change.
C. Stationary objects experience impulse.
D. The standard unit for impulse id the N-m.
A 8. All the following statements about collisions are true EXCEPT?
A. Two colliding bodies, say A and B, will exert equal forces upon each other even if their
masses are different.
B. In collision, a body always experiences an impulse and a change in momentum.
C. In collision, the impulse which a body experiences is the same as its velocity.
D. In collision, two colliding bodies could have varied acceleration values. D 9. Which of the following
statements is true about momentum?
A. Most collisions tend to be partially elastic then become completely elastic.
B. Momentum is only conserved in elastic collision but not in inelastic collision.
C. The kinetic energy of an object remains constant during an elastic collision.
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D. Elastic collisions occur when the collision force is a non-contact force.
B. 10. Which of the following has the greatest amount of momentum in relation to the earth?
A. a mountain climber trailing Mount Apo
B. a delivery truck speeding along a highway
C. a car truck parked in a parking lot
D. the Social Science building on the university campus
II. Problem Solving
Solve the following problems with complete solutions.
1.) Initially an automobile is heading towards north at the rate of 27.6 m/s. Finally, the speed was
reduced to 4.20 m/s in the same direction. The automobile’s change in momentum is 10, 500
kg- m/s. Find the mass of the ball.
2.)
A
sled, with a mass of 1..40 x 102 kg travels at constant force in 4.75 s. The velocity of the sled
is initially zero and the final velocity is 7.95 m/s.(a) What is the change in momentum? (b)
What net force is exerted on the sled?
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3.) To improve the safety of motorists, modern cars are built so the front end crumples upon
impact. A 1200 kg car is travelling at a constant velocity of 8.0 m/s. It hits an immovable wall
and comes to a complete stop in 0.25 s
a. Calculate the impulse provided to the car.
b. What is the average net force exerted on the car?
c. For the same impulse, what would be the average net force exerted on the car if it has a
rigid bumper and frame the car in 0.040 s?
4.) In a tennis game, a 0.2 kg ball moving at 15 m/s is hit by a racket. After the impact the ball
moves in the opposite direction with a velocity of 20 m/s. If the force F exerted on the ball by
the racket is 700 N, how long is the time contact?
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