Question
A resultant force of 500 N acts for 10 s on a car of mass 1000 kg. This causes the velocity of the car to double.
What is the final velocity of the car?
A 5 m / s B 10 m / s C 20 m / s D 50 m / s
Answer/Explanation
Ans:
B
Question
Two objects $X$ and $Y$ move directly towards each other. The objects have the same mass.
Object $X$ has a velocity of $5.0 \mathrm{~m} / \mathrm{s}$ to the right. Object $Y$ has a velocity of $3.0 \mathrm{~m} / \mathrm{s}$ to the left.
Object $X$ and object $Y$ collide and stick together.
What is their velocity after colliding?
A $1.0 \mathrm{~m} / \mathrm{s}$ to the left
B $1.0 \mathrm{~m} / \mathrm{s}$ to the right
C $4.0 \mathrm{~m} / \mathrm{s}$ to the left
D $4.0 \mathrm{~m} / \mathrm{s}$ to the right
Answer/Explanation
Ans:B
Question
A gas molecule strikes the wall of a container. The molecule rebounds with the same speed. 
What happens to the kinetic energy and what happens to the momentum of the molecule?
kinetic energy | momentum | |
A | changes | changes |
B | changes | stays the same |
C | stays the same | changes |
D | stays the same | stays the same |
Answer/Explanation
Ans: C
Question
A tennis ball has a mass of 57 g.
A tennis player hits the tennis ball with a tennis racket. The tennis ball has a velocity of 25 m / s when it hits the racket.
The velocity of the tennis ball when it leaves the player’s racket is 15 m / s in the opposite direction from its approaching direction.
The average force exerted by the tennis racket on the ball is 35 N. For how long is the tennis ball in contact with the tennis racket?
A 0.015 s B 0.016 s C 0.065 s D 0.65 s
Answer/Explanation
Ans: C
Question
An air pistol fires a pellet forwards.
What is the motion of the air pistol?
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The air pistol moves backwards with speed greater than the pellet.
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The air pistol moves backwards with speed less than the pellet.
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The air pistol moves forward with speed greater than the pellet.
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The air pistol moves forward with speed less than the pellet.