Question

Mr. B wants to close a door that's across the room from him. He's too focused on writing good physics problems to get up from the couch and close the door himself. Using his knowledge of momentum, he realizes he can throw a pillow within arms reach at the door to close it. Using your knowledge of the conservation of momentum, explain how Mr. B is able to close the door with the pillow in terms of conservation of momentum. (anytime you see explain "in terms of" make sure you use that term in your explanation!)

Answer 1

Mr. B is able to close the door with the pillow by utilizing the conservation of momentum.

Step-by-step explanation:

In this scenario, Mr. B is able to close the door with the pillow by utilizing the conservation of momentum.

1. A closed system is defined as a system where no external forces act on it.

2. The expression for conservation of momentum is:

Minitial = Mfinal

3. The expression for conservation of kinetic energy is:

Kinitial = Kfinal

4. By throwing the pillow at the door, Mr. B transfers momentum from himself to the pillow. The momentum of the door+pillow system will be the same as the momentum of Mr. B before he threw the pillow, thus closing the door.