Question

Questions (use complete sentences)

1) What is a conservation law? What is the basic approach taken when using a conservation law?

2) Could the linear momentum of a turtle be greater than the linear momentum of a horse? Explain.

3) Carts A and B stick together whenever they collide. The mass of A is twice that of B. How could you roll the carts so that they would be stopped after a collision?

4) How can a satellite’s speed decrease without its angular momentum changing?

Problems (show your work)

1) What is the linear momentum of an object with mass 50 kg and speed 15 m/s?

2) A 0.25 kg ball of clay is thrown at a stationary 5 kg block of wood. The clay sticks to the wood and their velocity after is 3 m/s. What was the original velocity of the clay?

3) A 50 kg boy on skates moves with a speed of 5 m/s. He runs into a stationary girl with skates of mass 40 kg. Assuming they stick together, what is their speed after the collision?

4) A running back with a mass of 80 kg and speed 8 m/s collides with, and is held by, a 120 kg defensive tackle going in the opposite direction. How fast must the tackle be going before the collision for their speed afterward to be zero?

5) An object is pushed along a horizontal surface with a force of 10 N. If the object is moved 15 m, how much work does the pushing force do? How much work does gravity do?

6) As it orbits the Earth, the 11,000 kg Hubble Space Telescope travels at a speed of 7,900 m/s and is 560,000 m above the Earth’s surface. What is its kinetic and potential energy?

7) A child on a swing has a speed of 7.7 m/s at the low point of the arc. What will be the maximum height of the child?

8) If an object is thrown straight up and reaches a height of 20 m, what was the initial speed of the object?

9) An object of 2 kg is moving in a circle of radius 4 m and speed 0.5 m/s. What is the angular momentum of the object?

Challenges (show work)

1) A bullet of mass 0.01 kg is fired horizontally into a block of wood of mass 2 kg. The wood is hanging on a string initially at rest. When the bullet hits the wood it gets embedded into the wood then they swing upward to a height of 0.1 m. What was the initial speed of the bullet?

Answer 1