Question

A body is moving with uniform velocity of 2 m s­1 on a rough level surface. The frictional force on it is 10 N. If the body moves with velocity 4 m s­1 the force of friction will be: (a) 2.5 N (b) 5 N (c) 10 N (d) 20 N

Answer 1

Hey dear,

◆ Answer-
F2 = 20 N

◆ Explanation-
# Given-
v1 = 2 m/s
v2 = 4 m/s
F1 = 10 N

# Solution-
As we know, frictional force depends on the velocity of the moving object.
i.e. F ∝ v

Thus, here-
F1/v1 = F2/v2
F2 = F1 × v2 / v1
F2 = 10 × 4 / 2
F2 = 20 N

Therefore, frictional force is 20 N.

Hope it helps...

Answer 2

C)10N

Explanation:

AS BODY IS ALREADY IN MOTION ONLY KINETIC FRICTION IS APPLICABLE WHICH IS NOT SELF ADJUSTING LIKE STATIC FRICTION.

THEREFORE THERE WILL BE NO IMPACT ON THE FRICTIONAL FORCE(WHICH IS KINETIC IN NATURE)DUE TO ANY VELOCITY CHANGE.

SO ANSWER SHOULD BE 10N BECAUSE IT IS GIVEN THAT FRICTIONAL FORCE IS 10N.