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STD 11 - 5. work,energy,power and collision — JEE STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceJEESTD 11 - 5. work,energy,power and collision4 Marks
MCQ
A ball hits a vertical wall horizontally at $10m/s$  bounces back at $10 m/s$ 
  • A
    There is no acceleration because $10\,\frac{m}{s} - \,10\frac{m}{s} = 0$
  • B
    There may be an acceleration because its initial direction is horizontal
  • ✓
    There is an acceleration because there is a momentum change
  • D
    Even though there is no change in momentum there is a change in direction. Hence it has an acceleration
✓

Answer

Correct option: C.
There is an acceleration because there is a momentum change
c
(c)As the ball bounces back with same speed so change in momentum $= 2 mv$
and we know that force = rate of change of momentum
i.e. force will act on the ball so there is an acceleration.

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