Recent content by jasmine_01

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...