Practice Test Answers ! :)
| What is Mechanical Efficiency | Practice test | Practice test Answers | Bibliography |
1) Wout= F x d

Wout= 400N x 4m
Wout= 1600J

Win= F x d

Win= 250N x 8m

Win= 2000J

ME= Wout/Win
ME= 1600J/2000J
ME= 80%
The Mechanical Efficiency is 80%.
2) Wout= F x d
Wout= 10 000N x 5m
Wout= 50 000J

Win= F x d

Win= 7000N x 12m

Win= 84 000J

EW= Win - Wout
EW= 84 000J - 50 000J
EW= 34 000J

The Energy wasted is 34 000J.

3)Wout= F x d
Wout= 495N x 13m
Wout= 6435J

Win= F x d

Win= 385N x 25m

Win= 9625J

ME= Wout/Win x 100%
ME= 6435J/9635J x 100%
ME= 66.9%
The Mechanical Efficiency of this machine is 66.9%.
4) Work input- the total work a machine does.
Work output- the useful work a machine does.
5) The efficiency of a machine is never 100% because some of the force goes to over coming the force of friction and some is also turned into heat and sound energy.

| What is Mechanical Efficiency | Practice test | Practice Test Answers| Bibliography |