The mass of the long board is m = 100kg, the dynamic friction coefficient between the small block and the ground is U1 = 0.1, the mass of the small block is m = 100kg, and it starts to slide right on the long board from the left end at the initial speed V0 = 6m / s. The dynamic friction coefficient between the small block and the long board is U2. If the small block slides on the long board and the long board does not move, what conditions does U2 meet? What is the stress condition?

The mass of the long board is m = 100kg, the dynamic friction coefficient between the small block and the ground is U1 = 0.1, the mass of the small block is m = 100kg, and it starts to slide right on the long board from the left end at the initial speed V0 = 6m / s. The dynamic friction coefficient between the small block and the long board is U2. If the small block slides on the long board and the long board does not move, what conditions does U2 meet? What is the stress condition?

The positive pressure of the ground to the long board is: n = (M + m) g, the friction force of the small block to the long board is U1 * mg, and the maximum static friction force of the ground to the long board is U2 * n > = the friction force of the small block to the long board, so U2 > = 0.1