# objects A,B,C with masses m,2 m,and m are kept on a friction less horizontal surface. The object A move towards B with a speed of 9 m/s and makes an elastic collision with it . B makes completely inelastic collision with C. Then velocity of C is?

##### 2 Answers

With a completely elastic collision, it can be assumed that all the kinetic energy is transferred from the moving body to the body at rest.

#1/2m_"initial"v^2 = 1/2m_"other" v_"final"^2#

#1/2m(9)^2 = 1/2(2m)v_"final"^2#

#81/2 = v_"final"^2#

#sqrt(81)/2 = v_"final"#

#v_"final" = 9/sqrt(2)#

Now in a completely inelastic collision, all kinetic energy is lost, but momentum is transferred. Therefore

#m_"initial"v = m_"final"v_"final"#

#2m9/sqrt(2) = m v_"final"#

#2(9/sqrt(2)) = v_"final"#

Thus the final velocity of

Hopefully this helps!

#### Explanation:

The collision history can be described as

1) Ellastic collision

solving for

2) Inelastic collision

solving for