55. A person lifts luggage of 20 kg from the ground and puts it on his head 2m above the ground. Calculate the work done by him. (g = 10 ) A.20 J B.400J C.200J D.40J
Option B Solution: Total work done in lifting and moving the luggage is 588 Joules. Explanation : 1. work done in lifting the luggage = potential energy of the luggage = mgh where, m = mass = 20 kg g = acceleration due to gravity = 9.8 m/s² h = height = 3 m Hence, P = mgh = 20 x 9.8 x 3 = 588 J 2. work done in moving the object, Since now weight of the luggage is acting in downward direction and the movement is in horizontal direction, hence work done in moving the luggage is zero because component of force along horizontal direction is zero. Total work done = 588 + 0 = 588 J. Hence total work done in lifting and moving the luggage 588 J.
