Question

4. 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?
A) 640 joules
B) 78.4 joules
C) 189 joules
D) 145.6 joules


5. 1000 joules of energy are put into a pulley system, and 400 joules come out. What does the Law of Conservation of Energy imply about the lost energy?
A) The lost energy cannot be recovered.
B) The pulley system could be improved to conserve some of the lost energy.
C) The lost energy is caused by friction.
D) The lost energy is not truly lost, but it changed into a different form.

Answer 1

### Question 4
To find the total energy Ronald put into the inclined plane, we use the efficiency formula.

Efficiency (%) = (Output Energy / Input Energy) × 100

Given:
- Efficiency = 35%
- Output Energy = 224 joules

We need to find the Input Energy (which is what Ronald put into the system):

Efficiency = (224 joules / Input Energy) × 100

Rearranging the equation to solve for Input Energy:

Input Energy = Output Energy / (Efficiency / 100)

Input Energy = 224 joules / (35 / 100)
Input Energy = 224 joules / 0.35
Input Energy = 640 joules

So the answer is:
**A) 640 joules**

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### Question 5
The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed from one form to another or transferred from one system to another.

In this case:
- Input Energy = 1000 joules
- Output Energy = 400 joules
- Lost Energy = Input Energy - Output Energy = 1000 joules - 400 joules = 600 joules

Regarding the lost energy:
- It is not truly lost; it is transformed into other forms such as heat due to friction in the pulley system, etc.

Therefore, the correct answer is:
**D) The lost energy is not truly lost, but it changed into a different form.**