Honors Physics – Momentum Review Problems

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```					Honors Physics – Momentum Practice Problems

1.    Imagine that you are parked at a stop light. Suddenly your car is accelerated to a speed of 5 m/s by a
rear end collision. Your mass (in case you forgot) is 70 kg. Assume that the time of the collision is
0.3 s. a) Find the impulse on you and b) find the average force exerted on you by the back of the seat
of the car.

2.    A 16g mass is moving in the +x direction a 30 cm/s while a 4 g mass is moving in the –x direction at
50 cm/s. They collide head on and stick together. Find their velocity after the collision.

3.    A football of mass 0.42 kg is passed with a velocity of 25 m/s due south. A defending player lunges at
the ball and deflects it so that the new velocity is 20 m/s, 36.9 0 west of south. Find the magnitude of
the impulse. If the player is in contact with the ball for 0.05s, what is the magnitude of the average
force he exerts?

4.    A ghostly white Honda Civic with a mass of 1200 kg is moving east at 30 m/s and collides with a sky
blue Ford pick-up truck with a mass of 3600 kg moving at 20 m/s in a direction 60 0 north of east. The
vehicles interlock and move off together. Find their common velocity and the angle that describes
their new direction.

5.    Imagine that you are riding a skateboard at 3.2 m/s across a frictionless floor (technically, you are
sliding across the floor). The skateboard has a mass of 10 kg while you weigh 600 N. You jump off
the skateboard and land without injury on the floor at zero velocity. What impulse did you give to the
skateboard? What was the velocity of the skateboard after you jumped off?

6.    Suppose you have two putty balls (of the same mass) both moving along a frictionless floor with a
velocity of 45 m/s. They collide and stick together. Interestingly, their trajectories of travel leading to
the collision have an angle of 45o between them. Find their final velocity.

7.    Suppose that a horizontal force of 0.70 N is required to pull a 5 kg block across at a rough table at a
constant speed. What is the speed of a 20 g bullet, if the bullet embeds in the block and causes the
block to slide 1.5 m before coming to rest?

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Answers: 1a) 350 1b) 1167; 2) 0.14; 3) 6.3, 126; 4) 19.8, 40.9; 5) 196, 22.7 6) 41.58; 7) 163

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