Question

if a machine requires an input of 5,000 joules of work to put out 4,000 joules of work, what is the machines efficiency? a 100% b 60% c 80% d 40%

Explanation:

Step1: Recall the formula for efficiency

Efficiency ($\eta$) is given by the formula $\eta=\frac{W_{output}}{W_{input}}\times100\%$.

Step2: Substitute the given values

Here, $W_{output} = 4000$ J and $W_{input}=5000$ J. So, $\eta=\frac{4000}{5000}\times 100\%$.

Step3: Calculate the value

$\frac{4000}{5000}=0.8$, and $0.8\times100\% = 80\%$.

Answer:

C. 80%