physics homework help

Question

A 14.7 g bullet is fired into and embeds itself in a 2.9 kg block attached to a spring with a spring constant of 22.6 N/m and whose mass is negligible. How far is the spring compressed if the bullet has a speed of 279 m/s just before it strikes the block, and the block slides on a frictionless surface? Answer in units of m.

I'm getting 60.780 but it says I'm wrong

Answer 1

By law of conservation of momentum: mv₀ = (M + m)v; v = mv₀/(M + m) = 0.0147kg· 279m/s/(2.9kg + 0.0147kg) = 1.407 m/s.

Now by law of conservation of energy: (M +m)v²/2 = kx²/2; x = v√(M + m)/k = 1.407m/s√(2.9kg + 0.0147kg)/22.6N/m = 0.505 m