An electric pump raises 500kg of water from the ground into an overhead tank 15m above in 50s. A second pump of the same design raises the same amount of water through the same height in 80s.
a. (i) Write the expression for the average power developed by a pump while lifting water.
b. (ii) Calculate the average power output of each pump. Take g=9.8m s−2.
c. (iii) Determine the ratio of the average powers of the two pumps.
d. (iv) If both pumps momentarily deliver water at the same rate during start-up, explain why their instantaneous power outputs can still be equal even though their average powers differ.