[Leejohnston]

## Power = Energy ÷ Time — Why Watts Matter

### 1. The Equation

Power = Energy ÷ Time

Often written as:
P = E ÷ t

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### 2. What Each Symbol Means

- P = power (watts)
- E = energy (joules)
- t = time (seconds)

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### 3. What the Equation Is Telling Us

Power measures **how fast energy is being used or transferred**.

Using lots of energy slowly can mean low power.
Using the same energy quickly means high power.

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### 4. Where It Comes From (Intuition)

Power answers the question:
“How intense is this process right now?”

A kettle and a candle both release energy —
the kettle just does it much faster.

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### 5. Worked Example

If a device uses:
- 600 joules
- in 3 seconds

Power = 600 ÷ 3
= **200 watts**

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### 6. Real-World Applications

- Electricity bills
- Engine performance
- Human output (athletes)
- Computing and electronics

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### 7. Common Misconceptions

- Power and energy are the same → false
- High power always means wasteful → false
- Watts measure energy → false

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### Try It Yourself

How much power is used if:
- 1,000 joules are used in 10 seconds?