Given in the figure are two blocks A and B of weight 20 N and 100 N, respectively. These are being pressed against a wall by a force F as shown. If the coefficient of friction between the blocks is 0.1 and between block B and the wall is 0.15, the frictional force applied by the wall on block B is :
100 N
80 N
120 N
150 N
As we learnt in
Motion of Block in Contact -
- wherein
Static Friction -
Self adjusting force because it changes itself according with the applied force.
- wherein
It always equal to net external force. Static friction (F = P) using diag.
N = F
fr1 = 20 N
fr2 = 100 + 20 = 120 N
Where assume two blocks as one system due to equilibrium.
fr =120 N
Correct option is 3.
Option 1)
100 N
This is an incorrect option.
Option 2)
80 N
This is an incorrect option.
Option 3)
120 N
This is the correct option.
Option 4)
150 N
This is an incorrect option.
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