Class 9 Chapter Work and energy Solved Numerical problems 1. A force of 10N causes a displacement or 2m in a body in its own direction. Calculate the work done by force. 20j Solution: the work done by force = F x S = 10 N x 2m = 20 J 2. How much force is applied on the body when 150 joule of work is done in displacing the body through a distance of 10m in the direction of force?(15 N) Solution: W = F x S Þ F = w/s = 150/10 = 15 N 3. A body of 5kg raised to 2m find the work done(98j) Solution: T he work done to raise a body = PE = mgh = 5kg x 9.8 x 2 = 98 joule 4. A work of 4900j is done on road of mass 50 kg to lift it to a certain height. Calculate the height through which the load is lifted. (10m) Solution: work done on road to lift = mgh Þ 4900 = 50 x 9.8 h Þ h = 10m 5. An engine work 54,000J work by exerting a force of 6000N on it. What is the displacement of the force . (9m) Solution: S = W/F = 54,000J/6000N = 9m 6. A force of 10N acting on a body at an angle of 60 deg. with the
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