[Leejohnston]

## Conservation of Momentum — Why Rockets Work

### 1. The Equation

Total momentum before = total momentum after

p = mv

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### 2. What Each Symbol Means

- p = momentum
- m = mass
- v = velocity

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### 3. What the Equation Is Telling Us

Momentum is conserved in an isolated system.

If something moves one way, something else must move the other way.

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

Motion doesn’t disappear — it is redistributed.

Throwing mass backward pushes you forward.

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### 5. Worked Example

A rocket ejects exhaust backward →
the rocket gains forward momentum.

No air is required.

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### 6. Real-World Applications

- Rocket propulsion
- Collisions
- Recoil
- Space manoeuvres

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### 7. Common Misconceptions

- Rockets push on air → false
- Momentum and energy are the same → false
- Heavier exhaust always helps → false

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### Try It Yourself

Why does stepping off a boat push it backward?