As shown in the figure, when the board with length of L = 2M and mass of M = 8kg is placed on the horizontal ground, and the speed of the board moving to the right is v = 6m / s, a small block with mass of M = 2kg regardless of size is gently placed at the front end of the board. The dynamic friction coefficient between the board and the ground and between the block and the board is μ = 0.2, g = 10m / S2 (1) The acceleration of the block and the board; (2) the speed of the block sliding away from the board

As shown in the figure, when the board with length of L = 2M and mass of M = 8kg is placed on the horizontal ground, and the speed of the board moving to the right is v = 6m / s, a small block with mass of M = 2kg regardless of size is gently placed at the front end of the board. The dynamic friction coefficient between the board and the ground and between the block and the board is μ = 0.2, g = 10m / S2 (1) The acceleration of the block and the board; (2) the speed of the block sliding away from the board

(1) The friction between the block and the board makes the block and the board move together, and the acceleration am = μ g = 2m / S2. If the acceleration of the board is set as am, then: μ Mg + μ (M + m) g = mam. The solution is: am = 3m / s2 (2) the condition for the block to leave the board is that the relative displacement of the two is at least L. if the block slides from the board through ts, then