- #1
Taylor_1989
- 402
- 14
Homework Statement
A lift motor is 70% efficient. It dose 450 000j of work lifting a load to the top floor of a building.
Homework Equations
What electrical energy input is required to do this?
The Attempt at a Solution
I first did output/input * 100 I transposed the formulae
so I did 450 000* 0.7
which gave the wrong answer. When I looked at the answer is say this is the correct way is 450 000 * 100/70
Am I right in saying that when you do it this you are calculating what it is at 100% efficiency and then calculating the difference?