Question

If a body of mass m is moving on a rough horizontal surface of coefficient of kinetic friction µ, the net resultant force exerted by surface on the body is ______.

Options

• mg `sqrt(1+mu^2)`

• μmg

• mg

• mg `sqrt(1-mu^2)`

Answer 1

If a body of mass m is moving on a rough horizontal surface of coefficient of kinetic friction µ, the net resultant force exerted by surface on the body is `bb("mg" sqrt(1+mu^2))`.

Explanation:

The normal force and friction are the only resultant forces acting on the box.

f_k = µ mg

T.R. = `sqrt("N"^2+"f"_"k"^2)`

= `sqrt(("mg")^2+(mu"mg")^2)`

= mg `sqrt(1+mu^2)`