ch 8 phys quiz
Block A on the left has mass 1.00 kg. Block B on the right has mass 3.00 kg. The blocks are forced together, compressing the spring. Then the system is released from rest on a level, frictionless surface. After the blocks are released, how does KA (the kinetic energy of block A) compare to KB (the kinetic energy of block B)? A. KA = KB/9 B. KA = KB/3 C. KA = KB D. KA = 3KB E. KA = 9KB
D
Car #1 is going 50 mi/h when it crashes into a stationary wall and comes to a halt. An identical car #2 is going 50 mi/h when it crashes head-on into, and sticks to, identical car #3 going 50 mi/h in the opposite direction. Which statement is correct? A. Car #1 loses more momentum and more kinetic energy in its collision than does car #2. B. Car #1 loses more momentum, but the same amount of kinetic energy, in its collision than does car #2. C. Car #1 loses the same amount of momentum, but more kinetic energy, in its collision than does car #2. D. Car #1 loses the same amount of momentum and the same kinetic energy in its collision as does car #2. E. none of the above
D
Rank the following objects in order of the magnitude of the momentum of the object, from largest to smallest. A.Mass = 2.0 kg, kinetic energy = 2.0 J B.Mass = 1.0 kg, kinetic energy = 2.0 J C.Mass = 2.0 kg, kinetic energy = 4.0 J D.Mass = 4.0 kg, kinetic energy = 4.0 J
DCAB
Two objects with different masses collide with and bounce off each other. Compared to before the collision, the system of two objects after the collision has A. the same amount of total momentum and the same total kinetic energy. B. the same amount of total momentum but less total kinetic energy. C. less total momentum but the same amount of total kinetic energy. D. less total momentum and less total kinetic energy. E. Not enough information is given to decide.
E
A ball (mass 0.40 kg) is initially moving to the left at 30 m/s. After hitting the wall, the ball is moving to the right at 20 m/s. What is the impulse of the net force on the ball during its collision with the wall? A. 20 kg • m/s to the right B. 20 kg • m/s to the left C. 4.0 kg • m/s to the right D. 4.0 kg • m/s to the left E. none of the above
A
A yellow block and a red rod are joined together. Each object is of uniform density. The center of mass of the combined object is at the position shown by the black "X." Which has the greater mass, the yellow block or the red rod? A. The yellow block has the greater mass. B. The red rod has the greater mass. C. They both have the same mass. D. Either A or B is possible. E. A, B, or C is possible.
A
An open cart is rolling to the left on a horizontal surface. A package slides down a chute and lands in the cart. Which quantity or quantities have the same value just before and just after the package lands in the cart? A. the horizontal component of total momentum B. the vertical component of total momentum C. the total kinetic energy D. two of A, B, and C E. all of A, B, and C
A
A baseball is thrown vertically upward and feels no air resistance. As it is rising A) both its momentum and its mechanical energy are conserved. B) its momentum is not conserved, but its mechanical energy is conserved. C) both its momentum and its kinetic energy are conserved. D) its kinetic energy is conserved, but its momentum is not conserved. E) its gravitational potential energy is not conserved, buts its momentum is conserved.
B
Block A has mass 1.00 kg and block B has mass 3.00 kg. The blocks collide and stick together on a level, frictionless surface. After the collision, the kinetic energy (KE) of block A is A. one-ninth the KE of block B. B. one-third the KE of block B. C. three times the KE of block B. D. nine times the KE of block B. E. the same as the KE of block B.
B
Two objects with different masses collide with and stick to each other. Compared to before the collision, the system of two objects after the collision has A. the same amount of total momentum and the same total kinetic energy. B. the same amount of total momentum but less total kinetic energy. C. less total momentum but the same amount of total kinetic energy. D. less total momentum and less total kinetic energy. E. Not enough information is given to decide.
B
As a tile falls from the roof of a building to the ground its momentum is conserved. A) True B) False
B) False
A 3.00-kg rifle fires a 0.00500-kg bullet at a speed of 300 m/s. Which force is greater in magnitude: the force that the rifle exerts on the bullet or the force that the bullet exerts on the rifle? A. The force that the rifle exerts on the bullet is greater. B. The force that the bullet exerts on the rifle is greater. C. Both forces have the same magnitude. D. The answer depends on how the rifle is held. E. The answer depends on how the rifle is held and on the inner workings of the rifle.
C
A small glider is coasting horizontally when suddenly a very heavy piece of cargo falls out of the bottom of the plane. You can neglect air resistance. Just after the cargo has fallen out A) the plane speeds up and the cargo slows down. B) the plane speeds up but the cargo does not change speed. C) neither the cargo nor the plane change speed. D) the cargo slows down but the plane does not change speed. E) both the cargo and the plane speed up.
C
Block A on the left has mass 1.00 kg. Block B on the right has mass 3.00 kg. Block A is initially moving to the right at 6.00 m/s, while block B is initially at rest. The surface they move on is level and frictionless. What is the velocity of the center of mass of the two blocks after the blocks collide? A. 6.00 m/s, to the right B. 3.00 m/s, to the right C. 1.50 m/s, to the right D. zero E. Not enough information is given to decide.
C
Block A on the left has mass 1.00 kg. Block B on the right has mass 3.00 kg. Block A is initially moving to the right at 6.00 m/s, while block B is initially at rest. The surface they move on is level and frictionless. What is the velocity of the center of mass of the two blocks before the blocks collide? A. 6.00 m/s, to the right B. 3.00 m/s, to the right C. 1.50 m/s, to the right D. zero E. Not enough information is given to decide.
C
Block A on the left has mass 1.00 kg. Block B on the right has mass 3.00 kg. The blocks are forced together, compressing the spring. Then the system is released from rest on a level, frictionless surface. After the blocks are released, how does pA (the magnitude of momentum of block A) compare to pB (the magnitude of momentum of block B)? A. pA = pB/9 B. pA = pB/3 C. pA = pB D. pA = 3pB E. pA = 9pB
C
In a collision between two objects having unequal masses, how does magnitude of the impulse imparted to the lighter object by the heavier one compare with the magnitude of the impulse imparted to the heavier object by the lighter one? A) The lighter object receives a larger impulse. B) The heavier object receives a larger impulse. C) Both objects receive the same impulse. D) The answer depends on the ratio of the masses. E) The answer depends on the ratio of the speeds.
C
You are testing a new car using crash test dummies. Consider two ways to slow the car from 90 km/h (56 mi/h) to a complete stop: (i) You let the car slam into a wall, bringing it to a sudden stop. (ii) You let the car plow into a giant tub of gelatin so that it comes to a gradual halt. In which case is there a greater impulse of the net force on the car? A. In case (i). B. In case (ii). C. The impulse is the same in both cases. D. The answer depends on how rigid the front of the car is. E. The answer depends on how rigid the front of the car is and on the mass of the car.
C
