A laborer is throwing 12 bricks per min from the ground and these just reach the roof which is 3.3 meters high. if the weight of each bricks be 3.75 kg then find the horse power with which the laborer is working.
(1/12) * 60s = 5 s. per brick.
P = F * d/t = mg * d/t
P = 3.75*9.8 * 3.3/5=24.26 J/s=24.26 W.
(24.26/746) * 1hp = 0.0325 hp.