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Q4.18: NCERT Physics - Part 1 LAWS OF MOTION 4.18 Solution: Two billiard balls each of mass 0.05 kg moving in opposite…
⚠️ Common Exam Traps & Conceptual Pitfalls
Students often compute impulse as $\Delta p = p_{i}-p_{f}$ or ignore the sign change when the ball rebounds, yielding a wrong sign or half the correct magnitude. Remember that impulse is the vector change $\Delta p = p_{f}-p_{i}$; for a reversal $p_{f}=-p_{i}$, so $\Delta p = -2p_{i}$ and its magnitude is $2mv$.
Two billiard balls each of mass 0.05 kg moving in opposite directions with speed 6 m s__ collide and rebound with the same speed. What is the impulse imparted to each ball due to the other?
Step-by-Step Verified Solution
**Answer:** Impulse = 0.6 kg m/s
**Step-by-Step Explanation:**
Initial momentum of each ball = �0.05 _ 6 = �0.3 kg m/s.
After collision, momentum reverses: �0.3 kg m/s becomes _0.3 kg m/s.
Impulse = change in momentum = 0.3 - (-0.3) = 0.6 kg m/s [citation:10].
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