[Leejohnston]

## Kinetic Energy — Why Speed Is So Powerful

### 1. The Equation

Kinetic Energy = ½ × mass × velocity²

KE = ½mv²

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### 2. What Each Symbol Means

- KE = kinetic energy
- m = mass
- v = velocity

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### 3. What the Equation Is Telling Us

Speed matters more than mass.

Doubling speed increases energy **four times**.

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

Energy depends on how fast motion is happening —
not just how heavy the object is.

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### 5. Worked Example

If:
- mass = 1,000 kg
- speed = 10 m/s

KE = ½ × 1,000 × 10²
= **50,000 joules**

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### 6. Real-World Applications

- Car crashes
- Sports impacts
- Weapon physics
- Engineering safety limits

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### 7. Common Misconceptions

- Heavy always means dangerous → false
- Speed increases energy linearly → false
- Momentum and energy are interchangeable → false

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### Try It Yourself

What happens to kinetic energy if speed doubles?