Posted by **Rob** on Saturday, October 27, 2012 at 8:49pm.

A bullet of mass m=0.060 kg hits a 5.0 kg block with an initial speed of 225 m/s. The block is connected to a spring that is attached to a wall. The friction between the block and the table is negligible. Upon impact, the bullet bounces back from the box with a speed of 75 m/s.

A) Calculate the speed of the block right after the collision.

B) As a result of the collision, the spring compresses to a mazimum of 0.20m. Find the spring constant

--The equation to this is 1/2mv^2 = 1/2kx^2 right? I can't get the answer to this question without the answer to part A.

C) Find the inelastic energy loss during the collision.

- Physics -
**bobpursley**, Saturday, October 27, 2012 at 9:17pm
a. Momentum conserved. m*225=(5+.06)V

solve for V

- Physics -
**Rob**, Saturday, October 27, 2012 at 9:50pm
I got 2.67 m/s from your equation. But the correct answer is supposed to be 3.6 m/s.

- Physics -
**Rob**, Saturday, October 27, 2012 at 10:06pm
Also, for part C, do I do KE final minus KE initial?

So 1/2(5.06)(75^2) - 1/2(0.06)(225^2) ?

- Physics -
**Ricky**, Sunday, October 28, 2012 at 10:40pm
the correct equation is this: (.06)(225) = (5)(v) - (.06)(75)

momentum is conserved. total momentum is equal to the momentum of the block minus the momentum of the bullet. you subtract because the two objects move in opposite directions.

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