Physics · 2025
JEE Main · 29 January 2025, Shift 2 · Q28
Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Three identical spheres of…
Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) :
Three identical spheres of same mass undergo one dimensional motion as shown in figure with initial velocities $\displaystyle v_{\mathrm{A}}=5 \mathrm{~m} / \mathrm{s}, v_{\mathrm{B}}=2 \mathrm{~m} / \mathrm{s}, v_{\mathrm{C}}=4 \mathrm{~m} / \mathrm{s}$. If we wait sufficiently long for elastic collision to happen, then $\displaystyle v_{\mathrm{A}}=4 \mathrm{~m} / \mathrm{s}, v_{\mathrm{B}}=2 \mathrm{~m} / \mathrm{s}$, $\displaystyle v_{\mathrm{C}}=5 \mathrm{~m} / \mathrm{s}$ will be the final velocities.
Reason (R) : In an elastic collision between identical masses, two objects exchange their velocities.
In the light of the above statements, choose the correct answer from the options given below :
Three identical spheres of same mass undergo one dimensional motion as shown in figure with initial velocities $\displaystyle v_{\mathrm{A}}=5 \mathrm{~m} / \mathrm{s}, v_{\mathrm{B}}=2 \mathrm{~m} / \mathrm{s}, v_{\mathrm{C}}=4 \mathrm{~m} / \mathrm{s}$. If we wait sufficiently long for elastic collision to happen, then $\displaystyle v_{\mathrm{A}}=4 \mathrm{~m} / \mathrm{s}, v_{\mathrm{B}}=2 \mathrm{~m} / \mathrm{s}$, $\displaystyle v_{\mathrm{C}}=5 \mathrm{~m} / \mathrm{s}$ will be the final velocities.
Reason (R) : In an elastic collision between identical masses, two objects exchange their velocities.
In the light of the above statements, choose the correct answer from the options given below :Official answer
From NTA’s final answer key for this paper.
(4)
(A) is false but (R) is true
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JEE Main 2025 Physics question, with the answer from NTA’s final answer key. Where our answers come from.