bill does 1500 j of work on a lever, which is a simple machine. the lever does 1350 j of work on a stone…

Explanation:

Step1: Recall efficiency formula

The formula for efficiency $\eta$ of a machine is $\eta=\frac{W_{out}}{W_{in}}\times100%$, where $W_{out}$ is the output work and $W_{in}$ is the input work.

Step2: Identify input and output work

Given that the input work $W_{in}=1500\ J$ (work done on the lever) and the output work $W_{out} = 1350\ J$ (work done by the lever on the stone).

Step3: Calculate efficiency

Substitute the values into the formula: $\eta=\frac{1350}{1500}\times 100%$. First, $\frac{1350}{1500}=0.9$, then $0.9\times100% = 90%$.

Answer:

90%