physics
posted by Tom .
A 4.7 g bullet is fired horizontally into a 0.50 kg block of wood resting on a frictionless table. The block, which is attached to a horizontal spring, retains the bullet and moves forward, compressing the spring. The blockspring system goes into SHM with a frequency of 8.0 Hz and an amplitude of 15 cm. Determine the initial speed of the bullet. (answer should be in m/s)

k=M•ω²=M•(2•π•f)²=0.5(2•π•8)² = 1263.3 N/m
(m+M)•u²/2=k•x²/2
u=x•sqrt(k/(m+M)= 0.15•sqrt(1263.3/0.5047) =7.5 m/s.
m•v=(m+M)•u,
v=(m+M)•u/m =0.5047•7.5/0.0047=805.7 m/s