Physical science

Question

A man loads 1,000 sacks of flour into a truck in 30.0 minutes. Each sack has a mass of 20.0kg and the man must lift each sack 1.00 m from a cart up onto the truck bed. How much power did the man develop?

Answer 1

P = power = work / (time interval)

 

W = work

t = time = (30.0)(60) s = 1800 s

n = number of sacks = 1000

m = mass of 1 sack = 20.0 kg

h = height the sacks were lifted to = 1.00 m

g = acceleration of gravity = 9.8 m/s²

 

W = n(mgh)

 

P = W/t

 

P = 1000[20.0(9.8)(1.00)] / (1800) J/s ≅ 108.9 watts