Question

a body of mass 10kg is moving on an inclined plane of inclination 30 degree with an acceleration of 2ms .the body starts from rest the work done by force of gravity in 2s is
1) 10J
2) 0
3) 98 J
4) 196 J

Answer 1

Answer:

(4) 196 J

Explanation:

if the friction is zero, then a = g sin(30°) = 9.8/2 = 4.9 m/s^2

but, here a = 2 m/s^2 (given)

so, some work is done against friction.

work done by gravity= force due to gravity × disp.

= mg sin(30) × L

where, L - total displacement on the plane

using, s = ut + 1/2 a t^2

=> L = 0 + (1/2) × 2 × 2^2 = 4 m

work done by gravity = 10 × 9.8 × (1/2) × 4

= 196 J