300 J of work is to be done in lifting a bag of mass 5 kg in weight up to height of 4 m from the ground. What will be the acceleration with which the bag was revised?
Given, mass, m = 5 kg, work, W = 300 J h = 4 m, g = 10 ${{ms}^{-2}}$
Work done, W = mgh + mah = m(g + a)h =
300 = 5 x (10 + a) x 4
=> 300 = 20(10 + a)
10 + a = 300/20 = 15
a = 15-10 = 5 ${{ms}^{-2}}$