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JEE Main 202331 JanuaryMorning Shift
Exam
JEE Main
Year
2023
Date
31 January
Shift
Morning Shift
Subject
Physics
Chapter
Center of Mass, Momentum and Collision

JEE Main 2023 · 31 January · Morning Shift · Physics · Center of Mass, Momentum and Collision

100 balls each of mass m moving with speed v simultaneously strike...

100100 balls each of mass mm moving with speed vv simultaneously strike a wall normally and reflected back with same speed, in time tsts. The total force exerted by the balls on the wall is100 balls each of mass m moving with speed v simultaneously strike a wall normally and reflected back with same speed,

Options

  1. A100mvt\dfrac{100mv}{t}
  2. B200mvt\dfrac{200mv}{t}
  3. C200mvt200mvt
  4. Dmv100t\dfrac{mv}{100t}

Correct answer

B. 200mvt\dfrac{200mv}{t}

Step-by-step solution

100 balls each of mass m moving with speed v simultaneously strike a wall normally and reflected back with same speed,.

Force exerted by each ball is F=∆p∆tF = \dfrac{∆ p}{∆ t}, here, pp is momentum and tt is time.

So, for one ball F=mv−m(−v)t=2mvtF = \dfrac{mv - m\left(- v\right)}{t} = \dfrac{2mv}{t}

Now, total force exerted by the balls on the wall is Fnet=100×F=200mvt{F}_{net} = 100 \times F = \dfrac{200mv}{t}.

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