Number 4

An object that has momentum can NOT also be _______________.

• at rest

• in free-fall motion

• Slowing Down

• moving along a circular path

Compared to Object B, Object A has __________ the momentum.

• Four times

• Two times

• Eight times

• One-half

A 5.0-kg object moving at 2.0 m/s experiences a 20-Newton resistive force over a duration of 0.20 sec. What is the impulse experienced by the object?

• 4.0 N•s

• 10.0 kg•m/s

• 2.0 kg•m/s

A football player is running down the field. He has 280 kg•m/s of northward momentum. He experiences a southward impulse of 120 N•s. What is the final momentum (magnitude and direction) of the player?

• 160 kg•m/s, northward

• 400 kg•m/s, northward

• 400 kg•m/s, southward

• 160 kg•m/s, southward

In a classroom demonstration, two students of equal-mass stand on skateboards facing each other and initially at rest. Student A gives Student B a hard, quick push horizontally. Which of the following statements describes the resulting motion of the two carts? Assume the students do not fall off their skateboards.

• Student A will remain stationary; student B will be propelled rightward.

• Student A will move backwards slightly; student B will be move rightward with a large momentum.

• Student A will move backward with large momentum; student B will move to the right slightly

• Student A and student B will move away from each other with the same speed.

Two carts of unequal mass are involved in a collision. How does the force acting upon the 0.5-kg cart compare to the force that acts upon the 1.0-kg cart?

• Both carts experience the same force.

• The force on the 0.5-kg cart is one-half the magnitude of the force on the 1.0-kg cart.

• The force on the 0.5-kg cart is one-quarter the magnitude of the force on the 1.0-kg cart.

• The force on the 0.5-kg cart is twice the magnitude of the force on the 1.0-kg cart.

Two carts with a mass of 0.5-kg are positioned next to one another on a low-friction track. A spring-loaded plunger is released, propelling the carts away from one another in an explosion. The cart on the left begins moving with a speed of 40 cm/s. With what speed will the cart on the right begin moving?

• 20 cm/s

• 40 cm/s

• 80 cm/s

• It is impossible to predict with so little information.

Two carts with masses of 0.5 kg and 2.0 kg are positioned next to one another on a low-friction track. A spring-loaded plunger is released, propelling the carts away from one another in an explosion. After the collision the cart on the 0.5 kg cart moves to the left with a speed of 40 cm/s. With what speed will the cart on the right move after the collision?

• 10 cm/s

• 40 cm/s

• 160 cm/s

• It is impossible to predict with so little information.

A small fish is at rest in the water. A big fish with four times the mass is gliding along with a speed of 20 cm/s. The big fish opens its mouth and captures the smaller fish. With what speed do the two fish glide through the water after the collision?

• The same speed - 20 cm/s.

• With a much slower speed - perhaps 5 cm/s.

• With a slightly slower speed - perhaps 16 cm/s.

• With a slightly faster speed - perhaps 25 cm/s.

• With a much faster speed - perhaps 80 cm/s.

Block X of mass 2kg and block Y of unknown mass travel toward each other. An elastic collision occurs in which momentum is conserved. The graph above shows the velocity of block X and of velocity of block Y as a function of time before, during, and after the collision. What is the mass of block Y?

• 0.4kg

• 2kg

• 6kg

• 30kg