Impulse and Momentum Change
J = integral F dt = p_f - p_i; signs are essential for rebounds and reversals.
Why this shows up in the exam
Collisions · Force-time graphs · Catching problems
Learn the idea
Impulse is force-time area and equals the vector change in momentum. A momentum change can come from a strong short force or a weaker long force.
🧠 Memory hook: Area under F-t equals change in p.
Get this one clearly and it pays off every single time it shows up in the paper. 🎯
Formulas & facts to keep ready
- J = integral F dt = Delta p — impulse theorem
- F_avg = Delta p/Delta t — average contact force
- F = dp/dt — p-t graph slope
How to approach it
- 1Choose a positive direction
- 2Compute p_f-p_i
- 3Use area or contact time
Common slip-ups that cost marks
- •Adding rebound magnitudes
- •Using peak as average force
- •Missing unit conversions
🌟 That's the whole idea — you've got this. Try the practice set below; every question you attempt makes it stick a little harder.
Original chapter practice
Original questions for this chapter, not past-paper questions or an exact mapping to this individual concept.
A 2 kg block moves on a horizontal rough surface with coefficient of kinetic friction 0.2. A horizontal force of 10 N acts on it. Take g = 10 m/s^2. What is its acceleration?
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