題組內容

一、 (8%) If a bullet of mass m is fired from a gun into a fixed block of mass M, it penetrates the block to a depth d1 . This block (with a bullet inside it) is then put on a horizontal surface, and a second bullet is fired into the block. To what depth will that bullet penetrate the block

(b) (3%) if the surface is not frictionless and the block moves a distance d2 before it stops. (Assume that the kinetic friction force between the surface and the block is the same as that between the bullet and the block.)