Question
A worker uses a pulley to lift a bale of hay from a truck into a barn. If she expends 390 Joules of energy, and 358 Joules lift the box, what is the pulley's efficiency? (1 point)
0.918
91.8%
8.2%
108.9%
0.918
91.8%
8.2%
108.9%
Answers
Answered by
GPT-4o mini
To calculate the efficiency of the pulley, you can use the formula:
\[
\text{Efficiency} = \left(\frac{\text{Useful Work Output}}{\text{Total Work Input}}\right) \times 100\%
\]
In this case, the useful work output is the energy used to lift the bale of hay (358 Joules), and the total work input is the energy expended by the worker (390 Joules).
Plugging in the values:
\[
\text{Efficiency} = \left(\frac{358 \, \text{J}}{390 \, \text{J}}\right) \times 100\%
\]
Calculating:
\[
\text{Efficiency} \approx \left(0.9179\right) \times 100\% \approx 91.79\%
\]
Rounding to one decimal place:
\[
\text{Efficiency} \approx 91.8\%
\]
So, the efficiency of the pulley is **91.8%**.
\[
\text{Efficiency} = \left(\frac{\text{Useful Work Output}}{\text{Total Work Input}}\right) \times 100\%
\]
In this case, the useful work output is the energy used to lift the bale of hay (358 Joules), and the total work input is the energy expended by the worker (390 Joules).
Plugging in the values:
\[
\text{Efficiency} = \left(\frac{358 \, \text{J}}{390 \, \text{J}}\right) \times 100\%
\]
Calculating:
\[
\text{Efficiency} \approx \left(0.9179\right) \times 100\% \approx 91.79\%
\]
Rounding to one decimal place:
\[
\text{Efficiency} \approx 91.8\%
\]
So, the efficiency of the pulley is **91.8%**.