MHT CET · Physics · Center of Mass Momentum and Collision
'N' number of balls of mass ' \(\mathrm{m}^{\prime} \mathrm{kg}\) moving along positive direction of \(\mathrm{x}\) - axis, strike
a wall per second and return elastically. The velocity of each ball is 'u' \(\mathrm{m} / \mathrm{s}\). The
force exerted on the wall by the balls in newton, is
- A \(\mathrm{m} \mathrm{Nu}\)
- B 0
- C \(2 \mathrm{mNu}\)
- D \(\frac{\mathrm{mNu}}{2}\)
Answer & Solution
Correct Answer
(C) \(2 \mathrm{mNu}\)
Step-by-step Solution
Detailed explanation
force exerted on the \(=\frac{\text { change in momentom }}{\text { Time }}\) wall
Now, Initial momentum \(=N\) mu i
Final momentum \(=-N m v \hat{i}\)
Net change \(=2 \mathrm{Nmu}\)
\(\begin{aligned} \text { Force } &=\frac{\text { momentum change }}{1 \text { qec }} \\ &=\frac{2 \mathrm{Nm} \cup}{\text { Coption } 3 \text { iscorrecto }} . \end{aligned}\)
Now, Initial momentum \(=N\) mu i
Final momentum \(=-N m v \hat{i}\)
Net change \(=2 \mathrm{Nmu}\)
\(\begin{aligned} \text { Force } &=\frac{\text { momentum change }}{1 \text { qec }} \\ &=\frac{2 \mathrm{Nm} \cup}{\text { Coption } 3 \text { iscorrecto }} . \end{aligned}\)
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