Q. 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 :

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A

Increase

B

Decrease

C

Remain the same

D

May increase or decrease

Solution:

Contact force is the resultant of normal reaction and the friction acting on the body. If the angle between the contact force and vertical is decreases then its horizontal component which is friction will decrease.

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