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Momentum

Year 9 🚀 Forces & Motion Calculate momentum p = mv; understand impulse and conservation.

Momentum is a measure of how difficult it is to stop a moving object. A heavy, fast object has lots of momentum.

Momentum

$$p = mv$$

$p$ = momentum (kg m/s) · $m$ = mass (kg) · $v$ = velocity (m/s)

In a closed system (no external forces), the total momentum before a collision equals the total momentum after.

Conservation of Momentum

$$m_1v_1 + m_2v_2 = m_1v_1' + m_2v_2'$$

Example: 2 kg ball at 3 m/s hits stationary 1 kg ball. After: 2×3 = 2×v₁ + 1×v₂. Total momentum = 6 kg m/s.

Force × time = change in momentum (impulse). A large force applied for a short time, or a small force for a long time, can give the same impulse.

Impulse

$$F \Delta t = \Delta p = m \Delta v$$

🥊 Boxing gloves increase contact time → reduce force for same impulse → safer!

🎯 Ready to test yourself? Click the Quiz tab above to answer questions on this topic!

⚗️ 💥 Momentum Calculator

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