# Physics

You have been asked to design a "ballistic spring system" to measure the speed of bullets. A bullet of mass m is fired into a block of mass M. The block, with the embedded bullet, then slides across a frictionless table and collides with a horizontal spring whose spring constant is k. The opposite end of the spring is anchored to a wall. The spring's maximum compression d is measured.

(a) Find an expression for the bullet's initial speed in terms of m, M, k, and d.

I got this part right [Ans: (d/m)*sqrt(k*(m+M))]

(b) What was the speed of a 5.2 g bullet if the block's mass is 2.0 kg and if the spring, with k = 41 N/m, was compressed by 10 cm?

(c) What fraction of the bullet's energy is "lost"?

^How do I solve part (c)? Thanks

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1. you have the initial bullet KE (from initial speed0.

You have the spring final energy.

energy lost= iniial KE-finalPEspring

fraction=energy.lost/initialKE

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bobpursley

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