# Phsyics help!?

1. A student of mass m = 73 kg runs at a velocity vi = 1.53 m/s before jumping on a skateboard. After jumping on the board the student has a velocity vf = 1.45 m/s. What is the mass of the skateboard, in kilograms?

2. A student of mass m1 = 63 kg runs towards his skateboard, which has a mass m2 = 2.8 kg and is d = 2.95 m ahead of him. He begins at rest and accelerates at a constant rate of a = 0.75 m/s2. When he reaches the skateboard he jumps on it. What is the velocity of the student and skateboard in meters per second?

3. A crate of mass 54 kg containing bananas is sliding in a straight line on a frictionless surface at a constant velocity of 11 m/s. A monkey of mass 39 kg hanging from the ceiling times it correctly and jumps vertically down landing in the crate. At the time the monkey lands in the crate his velocity is 12 m/s vertically downward. What is the velocity, in meters per second, of the crate with monkey afterwards?

4. A runaway train car that has a mass of 14000 kg travels at a speed of 5.4 m/s down a track.

Randomized Variables

m = 14000 kg

v = 5.4 m/s

F = 1600 N

What is the time required for a force F to bring the car to rest, expressed in terms of m, v, and F?

5. Suppose that a garbage truck is 1.1 × 104 kg and is initially moving at 23.5 m/s. What is the speed of the garbage truck, in meters per second, just after it hits and adheres to a trash can that is 175 kg and initially at rest?

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