Question

efficiency of machines quick check
ronald pushes a box up an inclined plane with 35% efficiency. if 224 joules of energy went into moving the box, how much energy did ronald put into the inclined plane? (1 point)
640 joules
78.4 joules
145.6 joules
189 joules

Explanation:

Step1: Recall the efficiency formula

Efficiency $\eta=\frac{W_{output}}{W_{input}}\times100\%$. We know $\eta = 35\%=0.35$ and $W_{output}=224$ joules.

Step2: Solve for $W_{input}$

From $\eta=\frac{W_{output}}{W_{input}}$, we can rewrite it as $W_{input}=\frac{W_{output}}{\eta}$. Substitute the values: $W_{input}=\frac{224}{0.35}$.
Calculate $\frac{224}{0.35}=\frac{224\times100}{35}=\frac{22400}{35} = 640$.

Answer:

640 joules