Question

A 50.0 kg object rests on a horizontal surface. The coefficient of static friction between the box and the surface is 0.300 and the coefficient of kinetic friction is 0.200. What is the friction force on the object if a horizontal 140 N push is applied to it?

Answer 1

`f=140\ N`

Step-by-step explanation:

Given:

• mass of the object on a horizontal surface,
  `m=50\ kg`

• coefficient of static friction,
  `\mu_s=0.3`

• coefficient of kinetic friction,
  `\mu_k=0.2`

• horizontal force on the object,
  `F=140\ N`

Now the value of limiting frictional force offered by the contact surface tending to have a relative motion under the effect of force:

`F_s=\mu_s.N`

where:

`N=` normal force of reaction acting on the body= weight of the body

`F_s=0.3* (50* 9.8)`

`F_s=147\ N`

As we know that the frictional force acting on the body is always in the opposite direction:

So, the frictional force will not be at its maximum and will be equal in magnitude to the applied external force and hence the body will not move.

so, the frictional force will be:

`f=140\ N`