Question

A body of mass 2kg begins to slide down a plane inclined at an angle of 45° with the horizontal. The force of friction will be?

(a) 19.6sin 45°

(b) 9.8sin 45°

(c) 19.6cos 45°

(d) 9.8cos 45°

This question was posed to me in an interview for internship.

This question is from Friction and Motion in section Laws of Motion of Engineering Physics I

Answer 1

The correct answer is (a) 19.6sin 45°

To elaborate: When the body just slides down on the inclined plane,

f = mgsinθ = 2×9.8sin 45°

f = 19.6sin 45°.