An object of mass m moving at speed v0 strikes an object of mass ...

[frankwu]

An object of mass m moving at speed v0 strikes an object of mass 2m which had been at rest. The first object bounces backward along its initial path at speed v0 . Is this collision elastic, and if not, what is the change in kinetic energy of the system?
 a. The collision is elastic.
  b. The kinetic energy decreases by mv2.
  c. The kinetic energy decreases by mv2/2.
  d. The kinetic energy increases by mv2.

Question 2

A 26.0-g bullet moving at 1 200 m/s is fired through a one-kg block of wood emerging at a speed of 200 m/s. What is the kinetic energy of the block that results from the collision if the block had not been moving prior to the collision and was free to move?
 a. 6.6E+2 J
  b. 4.9E+2 J
  c. 3.4E+2 J
  d. 7.4E+2 J
  e. 1.3E+3 J

[ally]

Answer to Question 1

d

Answer to Question 2

c

[frankwu]

Gracias!

[juliaf]

Thanks for the timely response, appreciate it