Practice Problems

1. Consider a 0.1-kg coconut, falling from a tree 4-m above the ground. Find the following:

a. type (and amount) of energy before it falls
b. type (and amount) of energy right before it hits the ground
c. velocity right before it hits the ground
d. velocity at a point 1-m above the ground

2. Two toy cars collide on a track. A red car (0.2-kg) is traveling at 4 m/s and it smacks into the back end of a blue car (0.4 kg) traveling at 2 m/s in the same direction. They stick together. Find:

a. the type of collision that this is
b. the velocity of the red/blue cars (stuck together) immediately after the collision
c. what happens to the kinetic energy of the system before and after the collision. Calculate it, if you're not sure

3. Explain the following:

a. conservation of energy
b. conservation of momentum
c. elastic vs. inelastic collisions
d. the difference between mass and weight (and how to calculate it)

4. Two cars spring (explode) apart. If the first (1-kg) moves to the left at a final speed of 3 m/s, what is the speed of the second car (0.5-kg)?

5. Revisit the Newton's 2nd Law track problem: A 0.5-kg cart is pulled across a track by a string. The string is connected over a pulley to a 0.1-kg mass.

a. Find the acceleration of the cars
b. Find the acceleration of the cars if there is 0.5-N of friction between the car and track

6. How fast would a rollercoaster car have to travel so that you would just lose contact with the seat over a 5-m (radius) hill?