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## Homework Statement

A 15.0 g bullet with a speed of v = 235 m/s is fired into a block of wood that is initially at

rest on a frictionless surface. The block of wood is attached to a horizontal massless

spring with a spring constant k = 195 N/m that is initially uncompressed. The other end

of the spring is attached to a wall as shown in the figure below. The bullet becomes

imbedded in the block of wood which then compresses the spring a distance of 28.0 cm

before momentarily coming to a stop.

a) Determine the mass of the wooden block.

b) What fraction of the kinetic energy is transformed into other forms of energy

during the inelastic collision of the bullet with the wooden block?

## Homework Equations

## The Attempt at a Solution

for a) is it like this:

kx = 1/2mv^2

k=195

x = 28cm

m = m of bullet + M of block

v = initial speed

and then solve for M

kx = 1/2(m + M)^2.

And 2nd question i don't know how to start.