1Two construction cranes are each able to lift a maximum load of 20000 N to a height of 300 mHowever, one crane can lift that load in 1/5 the time it takes the other.How much more power does the faster crane have?(1) 25(2) 5(3) 1/25(4) Unable to determine.(5) 1(6) 1/5
The work done by both cranes is W Fd (20,000)(300) 6,000,000 J Let's say crane 1 lifts it in 5 secondsCrane 2 can lift it in 1/5 the time that crane 1 lifts so 1 secondFind the power for both P1 W/t 6,000,000/5 1,200,000 W P2 W/t 6,000,000/1 6,000,000 W Therefore, the faster crane has 5x the powerAnswer is (2) A quicker way to see this is that Power is indirectly proportional to timeReducing the time by 1/5 increases the power by a factor of 5.
