Question

In a situation the contact force by a rough horizontal surface on a body placed on it has constant magnitude. If the angle between this force and the vertical is decreased, the frictional force between the surface and the body will

Options

• increase

• decrease

•  remain the same

• may increase or decrease.

Answer 1

decrease

According to the first law of limiting friction,
f = μN
where f  is the frictional force
N is the normal reaction force
μ is the coefficient of static friction
and
N = mg － Fcosθ
where m is the mass of the body
F is the contact force acting on the body