Posted by Dee on .
A 10 g bullet is fired into, and embeds itself in, a 2 kg block attached to a spring with a force constant of 19.6 n/m and whose mass is negligible. How far is the spring compressed if the bullet has a speed of 300 m/s just before it strikes the block and the block slides on a frictionless surface? Use conservation of momentum.

Physics 2 
drwls,
Conservation of momentum tells you the velocity V' of the block and embedded bullet before the spring gets compressed.
0.010 kg*300 m/s = V' * (2.01 kg)
Solve for V'.
Energy is conserved during spring compression.
(1/2) k X^2 = (1/2) (M+m) V'^2
k is the spring force constant. M is block mass. m is bullet mass.
Solve for spring compression X