Question

Efficiency of Machines Quick Check Answers - Physical Science B

Which is the equation for a machine’s efficiency?
ANSWER - Efficiency=output energy (on top of) input energy ⋅ 100

A rotating space heater used 1,400 joules of energy while heating a room. Of that total, 896 joules produced thermal energy, 181 joules produced kinetic energy, 203 joules produced light energy, and 120 joules produced sound energy. What is the space heater’s efficiency?
ANSWER - 64%

Lenore is on an inclined plane next to her truck. Holding her hands steady, she pushes a box up the plane and into her truck. Where can energy be lost?
ANSWER - Friction between the box and the inclined plane.

Ronald pushes a box up an inclined plane with 35% efficiency. If 224 joules of energy went into moving the box, how much energy did Ronald put into the inclined plane?
ANSWER - 640 joules

1000 joules of energy are put into a pulley system, and 400 joules come out. What does the Law of Conservation of Energy imply about the lost energy?
ANSWER - The lost energy is not truly lost, but it changed into a different form.