6. A 0.03 kg bullet moving at 400.0 m/s penetrates 0.12 m into a solid wall and stops. a. How much kinetic energy did the bullet have?
b. How much work was performed by the wall to stop the block if there are no frictional losses?
c. How much force did the bullet apply to the wall?

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.15 times a second. a tack is stuck in the tire at a distance of 0.373 m from the rotation axis. noting that for every rotation the tack travels one circumference (a) find the tack's tangential speed. (b) what is the tacks radial acceleration?