Question

A machine uses 1000 J of electric energy to raise a heavy mass, increasing its potential energy by 300 J. What is the efficiency of this process?35%100%85%70%30%

Answer 1

30 %

Step-by-step explanation:

The efficiency of a machine is defined as:

where

`E_(useful)` is the useful output energy

is the energy in input

In this problem,

- The useful output energy is the increase in potential energy of the mass, so 300 J

- The energy in input to the machine is 1000 J

Therefore, the machine's efficiency is

`\epsilon = (300 J)/(1000 J)=0.30`

In percentage,

0.30 x 100 = 30 %