There is a board standing on a smooth horizontal plane, with mass of M = 4kg and length of L = 1.4m. At the right end of the board, there is a small block which can be regarded as a particle, with mass of M = 1kg, friction coefficient of u = 0.4 and g = 10m / S ^ 2. Now, the leveling force F acts on the board and makes m slide down from M. what is the minimum value of F?

There is a board standing on a smooth horizontal plane, with mass of M = 4kg and length of L = 1.4m. At the right end of the board, there is a small block which can be regarded as a particle, with mass of M = 1kg, friction coefficient of u = 0.4 and g = 10m / S ^ 2. Now, the leveling force F acts on the board and makes m slide down from M. what is the minimum value of F?

The force of two objects is analyzed
For M:
Ma1=F-umg
For M:
ma2=umg
If a small piece of wood falls, it actually means that two objects move differently, A1 > A2
LIANLI: F > 20n