Homework Statement
What is a situation where the efficiency of a device would change based on a redefinition of what is considered useful energy?[/B]Homework Equations
What would be considered useful energy?
How can the efficiency of a device change?[/B]The Attempt at a Solution
If heat or...
My attempt at finding the solutions:
(1) As part a) question asks about potential energy, the equation most relevant in this case would be Ep = mgh - where m is the mass, g is the gravitational force, and h is the height. It doesn't matter if the motor lifts the elevator itself or along with the...
Homework Statement
An elevator takes a 70 kg person from street level to the top of a 400 m sky-scraper in 4 minutes. The mass of the elevator is 500 kg.
a] At what rate is the elevator plus the person gaining potential energy?
b] What power is the elevator plus the person experiencing as...