ch 08 quiz 2

A table tennis ball launcher is fired. Compared to the force on the ball, the force on the launcher is

• larger.
• the same.
• smaller.

A table tennis ball launcher is fired. Compared to the impulse on the ball, the impulse on the launcher is

• smaller.
• larger.
• the same.

Momentum of a system is conserved only when

• there are no internal forces acting on the system.
• the system is not moving.
• there are no forces acting on the system.
• there is no net external force acting on the system.
• the system has zero momentum.

Suppose a girl is standing on a pond where there is no friction between her feet and the ice. In order to get off the ice, she can

• bend over touching the ice in front of her and then bring her feet to her hands.
• walk very slowly on tiptoe.
• get on her hands and knees and crawl off the ice.
• throw something in the direction opposite to the way she wants to go.
• all of the above will work

A cannon recoils from launching a cannonball. The speed of the cannon's recoil is small because the

• impulse on the cannon is less than the impulse on the cannonball.
• cannon has far more mass than the cannonball.
• momentum of the cannon is unchanged.
• force against the cannon is relatively small.
• none of the above

Suppose a cannon is made of a strong but very light material. Suppose also that the cannonball is more massive than the cannon itself. For such a system

• conservation of momentum would not hold.
• conservation of energy would not hold.
• the target would be a safer place than where the operator is located.
• the force on the cannonball would be greater than the force on the cannon.
• recoil problems would be lessened.

A cannon fires a cannonball. The speed of the cannonball will be the same as the speed of the recoiling cannon

• if the mass of the cannonball equals the mass of the cannon.
• because momentum is conserved.
• because velocity is conserved.
• because both velocity and momentum are conserved.
• none of the above

The force that accelerates a rocket into outer space is exerted on the rocket by

• the exhaust gases.
• Earth's gravity.
• atmospheric pressure.
• rocket's wings.
• none of the above

If all people, animals, trains and trucks all over the world began to walk or run towards the east, then

• Earth would spin a bit slower.
• Earth's spin would not be affected at all.
• Earth would spin a bit faster.

Suppose an astronaut in outer space wishes to toss a ball against a very massive and perfectly elastic concrete wall and catch it as it bounces back. If the ball is as massive as the astronaut, then

• the astronaut's time between catches will decrease as the game progresses.
• the astronaut will never catch the first bounce.
• the astronaut will catch one bounce only.
• none of the above