Sample 1Medium
A ball of mass 0.15 kg moving horizontally at 12 m s⁻¹ is hit straight back along its line of motion and leaves with the same speed of 12 m s⁻¹. The magnitude of the impulse imparted to the ball is
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The answer is A.
Impulse equals the change in momentum: m(v − u) = 0.15 × (12 − (−12)) = 0.15 × 24 = 3.6 N s, directed opposite to the initial motion.
- B.
1.8 N s is the initial momentum alone; the momentum is reversed, so its change is twice this.
- C.
0 N s treats the change in speed, not the change in velocity; momentum reverses direction.
- D.
7.2 N s is four times the initial momentum, double the actual change.
NCERT: Class 11 Physics, Chapter 4, Newton's second law of motion (impulse)