- #1

- 138

- 0

## Homework Statement

You have been asked to design a "ballistic spring system" to measure the speed of bullets. A bullet of mass 6.20 g is fired into a block of mass 2.10 kg. The block, with the embedded bullet, then slides across a frictionless table and collides with a horizontal spring whose spring constant is k=63.0 N/m. The opposite end of the spring is anchored to a wall. What was the speed of the bullet if the spring's maximum compression is 12.1 cm?

## Homework Equations

p

_{initial}=p

_{final}

E=0.5*k*x

^{2}

E= 0.5*m*v

^{2}

## The Attempt at a Solution

m1= bullet and m2= block; v1= vbullet

i first solved m

_{1}v

_{1}+m

_{2}v

_{2}= m

_{total}*v

_{final}for Vfinal..so that looked like v

_{final}= m1*v1/m

_{total }

then i used the energy equations to get 0.5*k*x

^{2}= 0.5*m*v

^{2}

in v2 i substituted m1*v1/m

_{total }

and then tried to solve for v1 which is the speed of the bullet we are looking for ...and my hwk app. is telling me my answer is wrong...so i was wondering if i made a mistake in the workings somewhere..