To find out how much energy Ronald put into the inclined plane, we can use the efficiency formula:
\[ \text{Efficiency} = \frac{\text{Useful Output Energy}}{\text{Input Energy}} \times 100% \]
In this case, we know the efficiency is 35% (or 0.35 in decimal form), and the useful output energy (that went into moving the box) is 224 joules. We need to find the input energy.
Rearranging the formula gives us:
\[ \text{Input Energy} = \frac{\text{Useful Output Energy}}{\text{Efficiency}} \]
Substituting the known values:
\[ \text{Input Energy} = \frac{224 \text{ joules}}{0.35} \]
Calculating this gives:
\[ \text{Input Energy} = 640 \text{ joules} \]
So, Ronald put 640 joules of energy into the inclined plane.
The correct answer is 640 joules.
1 answer