JEE Mains · Physics · STD 11 - Work,energy,power and collision
- JEE Mains 2021
- Hard
- Numerical
Three objects \(A, B\) and \(C\) are kept in a straight line on a frictionless horizontal surface. The masses of \({A}, {B}\) and \({C}\) are \({m}, 2\, {m}\) and \(2\, {m}\) respectively. \(A\) moves towards \({B}\) with a speed of \(9\) \({m} / {s}\) and makes an elastic collision with it. Thereafter \(B\) makes a completely inelastic collision with \(C.\) All motions occur along same straight line. The final speed of \(C\) is \(....\,{m} / {s}\)
Pick an option to check your answer.
Answer & Solution
Correct Answer
(A) \(4\)
Step-by-step Solution
Detailed explanation
After \(1^{st}\) collision
\(m v_{A}=m v_{A}^{\prime}+2 m v_{B}^{\prime}\)
\(-1=\frac{v_{B}^{\prime}-v_{A}^{\prime}}{0-v_{A}} \Rightarrow v_{B}^{\prime}=6 m / s\)
After the \(2^{nd}\) collision
\(2 mv _{ B }^{\prime}=(2 m + m )_{ V _{ C }}\)
\(\Rightarrow v _{ C }=\frac{2}{3} v _{ B }^{\prime} \Rightarrow v _{ C }=4 m / s\)
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