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A20 kg block is initally at rest. A 75 N...

A20 kg block is initally at rest. A 75 N force is required to set the block in motion. After the motion starts, a force of 60 N is required to keep the block moving with constant speed. The coefficient of static friction is

A

0.52

B

0.44

C

0.6

D

0.38

Text Solution

Verified by Experts

The correct Answer is:
D
A force of 75 N is required to set the block in motion i.e. 75 N is the limiting force of friction.
But F`=muR=muxxmg`
`:." "75=muxx20xx10`
`:." "mu=(75)/(200)=3/8=0.375=0.38`
This is the coefficient of static friction.
[Force of 60N corresponds to the dynamic friction.]
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