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
(a) increase
(b) decrease
(c) remain the same
(d) may increase or decrease.

Answer 1

Answer:

the answer is (a) i think so

just guessing

Answer 2

Answer:

(b) decrease

Explanation:

In the situation when the angle between the contact force and vertical decreases, friction force also decreases. Let the contact force has the magnitude F and it makes an angle θ with the vertical then Fcosθ will be the normal force on the body and Fsinθ will be the friction force. As F is constant , decrease in θ decreases Fsinθ and so friction.