Question

Calculate the efficiency for each machine, then answer the question. Machine A has an input work of 1,000 J and an output work of 250 J. Machine B has an input work of 500 J and an output work of 350 J. Machine C has an input work of 200 J and an output work of 150 J. Which machine is the most efficient?

Answer 1

Machine C. Machine A has an efficiency of 250/1000 = 0.25 = 25%, Machine B's efficiency is 350/500 = 0.7 = 70% and Machine C has an efficiency of 150/200 = 0.75 = 75%.

Answer 2

Explanation:

Efficiency is defined as the measure of amount of work done by a system.

Mathematically,        $Efficiency = \frac{Energy output}{Energy input} \times 100$

• For machine A efficiency will be as follows.

         Efficiency = $\frac{Energy output}{Energy input} \times 100$

                          = $\frac{250 J}{1,000 J} \times 100$

                          = 25%

• For machine B efficiency will be as follows.

  Efficiency = $\frac{Energy output}{Energy input} \times 100$

                          = $\frac{350 J}{500 J} \times 100$

                          = 70%

• For machine C efficiency will be as follows.

  Efficiency = $\frac{Energy output}{Energy input} \times 100$

                          = $\frac{150 J}{200 J} \times 100$

                          = 75%

Thus, we can see that efficiency is maximum in machine C, therefore, machine C is the most efficient.