A machine has an efficiency of 20 percent. Find the input work if the output work is 140 Joules

X = 700 Joules

Explanation:

The question asked about the efficiency of the work done.

The formula for efficiency is: Efficiency = (Useful output / input work) * 100%

The useful output given in the question is 140J, the question asked for input work. Let X be the input work. It is also given that the efficiency is 20%.

Using the formula of efficiency,

20 = (140/X) * 100

So, we simply solve the above equation.

X = 140*100/20

X = 700 Joules

The input work = 700 Joules

Explanation:

Given dа ta:

Efficiency = 20%

Output work = 140 joules

Input work = ?

The input work done can be calculated using the efficiency formula;

Efficiency = output work done/input work done * 100

Substituting, we have

20 = 140/Input work * 100

20 = 14000/input work

20*input work = 14000

input work = 14000/20

= 700 joules