Physics
posted by Joel on .
A 3kg mass moving initially to the right along the x axis with a speed of 8m/s makes a perfectly inelastic collision with a 5kg mass initially at rest at the origin.what fraction of the initial kinetic energy of the system is lost in the collision.what formula must i use.

The masses stick together so have the sum of masses and the same velocity after collision:
3*8 = 8 * v
v = 3 m/s after
Ke before = (1/2)(3)(64)
Ke after = (1/2)(8)(9)
answer = ( Ke before  Ke after)/Ke before