As shown in the figure, the bullet with mass m penetrates horizontally at velocity V0 and is placed on a smooth horizontal plane The bullet with mass m penetrates horizontally at velocity V0 on a smooth horizontal plane If the block mass m, the bullet mass m or the bullet initial velocity V0 changes, but the bullet can still pass through the block, then (assuming that the resistance of the block to the bullet and the block length remain unchanged) () A. If M remains the same, m becomes smaller and V0 remains the same, the kinetic energy obtained by the block will certainly increase B. If M becomes smaller, m remains unchanged, and V0 remains unchanged, the kinetic energy lost by the bullet must be smaller C. If M is constant, M is constant, and V0 is smaller, the kinetic energy obtained by the wood block must be constant D. No matter how V0, m and M change, the mechanical energy loss of the system will remain unchanged

As shown in the figure, the bullet with mass m penetrates horizontally at velocity V0 and is placed on a smooth horizontal plane The bullet with mass m penetrates horizontally at velocity V0 on a smooth horizontal plane If the block mass m, the bullet mass m or the bullet initial velocity V0 changes, but the bullet can still pass through the block, then (assuming that the resistance of the block to the bullet and the block length remain unchanged) () A. If M remains the same, m becomes smaller and V0 remains the same, the kinetic energy obtained by the block will certainly increase B. If M becomes smaller, m remains unchanged, and V0 remains unchanged, the kinetic energy lost by the bullet must be smaller C. If M is constant, M is constant, and V0 is smaller, the kinetic energy obtained by the wood block must be constant D. No matter how V0, m and M change, the mechanical energy loss of the system will remain unchanged

First, we can draw the V-T image of wood block and bullet. A: F remains unchanged, m acceleration remains unchanged, m acceleration becomes larger, when the relative displacement reaches L, the action time increases, and M velocity increases. Correct B: F remains unchanged, m acceleration decreases, and M acceleration remains unchanged. When the displacement reaches L, the action time increases, m velocity decreases, and kinetic energy loss increases