To find out how much energy Ronald put into the inclined plane, we can use the formula for efficiency:
\[ \text{Efficiency} = \frac{\text{Useful Energy Output}}{\text{Energy Input}} \times 100% \]
Given that the efficiency is 35% and the useful energy output (which is the energy effectively used) is 224 joules, we can rearrange the formula to find the energy input:
\[ \text{Energy Input} = \frac{\text{Useful Energy Output}}{\text{Efficiency}} \]
Since we need to express efficiency as a decimal for the calculation:
\[ \text{Efficiency} = 35% = 0.35 \]
Now we can substitute the values into the equation:
\[ \text{Energy Input} = \frac{224 \text{ joules}}{0.35} \]
Calculating this gives:
\[ \text{Energy Input} = \frac{224}{0.35} = 640 \text{ joules} \]
So, Ronald put 640 joules of energy into the inclined plane.
The answer is 640 joules.