Question

What is the efficiency of a machine that uses 102kj of enegery to do 98 kJ of work?

Answer 1

Answer: I got an increase of 306 kJ in internal energy.

Explanation: I used the 1st Law and the sign convention to get the answer in the screenshot.

(sorry if i'm wrong)

:(

Answer 2

The efficiency of the machine is 96.07%.

What is efficiency?

Efficiency can be defined as the ratio of work output to work input expressed in percentage.

To calculate the efficiency of the machine, we use the formula below.

Formula:

• E(%) = (Wo/Wi)100.......... Equation 1

Where:

• E(%) = Efficiency of the machine
• Wi = Work input of the machine
• Wo = Work output

From the question,

Given:

• Wi = 102 kJ
• Wo = 98 kJ

Substitute these values into equation 1

• E(%) = (98/102)100
• E(%) = 96.07%

Hence, the efficiency of the machine is 96.07%.

Learn more about efficiency here: