Question

a rifle bullet of mass 8.0g strikes and embeds itself in a block of mass 0.992kg that rests on a frictionless horizontal surface and is attached to a coil spring. the impact compresses the spring 15.0cm. calibration of the spring shows that a force of 0.750N is required to compress the spring 0.250cm.
a). find the magnitude of the velocity of the block just after impact.
b). what was the original speed of the bullet?

Answer 1

a)1/2mv^2 = 1/2kx^2
k=F/x = .75/.0025
so
1/2(.992)v^2 = 1/2(.75/.0025)(.15^2)
Solve for v
b)mv(bullet) = mv(block+bullet)
.008v = 1*v (you found in part a)