PHYSICS · Multi-part · CBSE · Physics · Work, Energy and Power · Work, Energy and Power
Problem
Two identical concrete blocks, each of mass 20kg, have to be lifted vertically through 1.8m. Student A lifts her block steadily and completes the task in 6s, while Student B does the same work in 3s.
(i) Explain the terms average power and instantaneous power with reference to mechanical work.
(ii) Without doing any numerical calculation, state which student develops the greater average power and justify your answer.
(iii) Calculate the average power developed by each student while lifting the blocks. (Take g=9.8m s−2.)
(iv) During Student B’s lift the block momentarily reaches an upward speed of 1.2m s−1. Determine the instantaneous power at that instant and compare it with the average power obtained in part (iii).