A 2 kg block with initial velocity +2m/s collides with a stationary 6 kg block with initial velocity 0m/s on a frictionless surface. After the collision, the 2 kg block is moving at –1 m/s and the 6kg block is moving to the right at +1 m/s.

Question

A 2 kg block with initial velocity +2m/s collides with a stationary 6 kg block with initial velocity 0m/s on a frictionless surface. After the collision, the 2 kg block is moving at –1 m/s and the 6kg block is moving to the right at +1 m/s.
Show that the total momentum is conserved in this collision 
is the collision elastic or inelastic ?

bobpursley · Answer

Initial momentum: 2*2=4 final momentum: 6(1)+2(-2)=4 initial KE=1/2 (2)2^2=4j final KE=1/2( 2(-1)^2+6(1)^2 )more energy? not elastic, some internal force added energy.