When the mass of the bullet is m, the displacement of the bullet and the block relative to the ground is S1 and S2 respectively, then S1: S2 () A. M+2mmB. 2M+mMC. M+mmD. Mm

When the mass of the bullet is m, the displacement of the bullet and the block relative to the ground is S1 and S2 respectively, then S1: S2 () A. M+2mmB. 2M+mMC. M+mmD. Mm

Let V 0 be the velocity before the sub ejection, and V be the velocity of the bullet and the block at last. From the time when the bullet hits the block to the time when the bullet is stationary relative to the block, the friction force between them is always F. according to the law of conservation of momentum, there is MV0 = (M + m) V, according to the theorem of kinetic energy, there are FS1 = 12mv 20 − 12mv 2, fs2 = 12mv 2