Question

A man pushes with a force of 150 N on a bookcase of mass 100 kg. The

coefficient of static friction between the bookcase and the floor is 0.65.
Because of friction, the bookcase does not move. What is the force of friction
on the bookcase?
O A. 100 N
O B. 150N
O C. 980 N
O D. 637 N

Answer 1

150 N

Step-by-step explanation:

Friction force always opposes, the relative motion between two bodies.

So whenever a force will be applied friction always try to oppose the motion that is being caused because if that force.

Maximum value of friction force is given by

Frictional force,
`Fr=\mu N=\mu mg`

Where
`\mu` is the Coefficient of static friction and N is the normal reaction between two surfaces, m is mass of the bookcase and g is acceleration due to gravity whose value is taken as
`9.81 m/s^(2)`

Substituting 100 kg for m,

`Fr=0.65*100*9.81=637.65\approx 637.7 N`

Now this force is less than the applied force, so the block will not move and friction force will be less than the maximum value.

Now in such cases, value of friction force is same as of that force which is causing the relative motion.

So in this case, friction force will be 150N.