It is known that the dynamic friction coefficient between the block and the table is 0.2, and the maximum static friction between the block and the table is 5 N. Two horizontal forces f '= 10N and f' '= 6N are applied on the block (1) Find the size and direction of the friction force on the block (2) If the external force F 'is removed, what is the magnitude and direction of the friction force on the block?

（1）F=μm
F=0.2*（10+5）=3N
F=0.2*（6+5）N=2.2N
（2）F=μm
F=0.2*5=1N
The top is the size, the direction is horizontal

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