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← JEE Main 2022 · 27 Jul · Shift 1
PhysicsInteger+4 / -1Question 57 of 90

JEE Main 2022 · 27 Jul · Shift 1, Physics question 57

A mass 0.9 kg, attached to a horizontal spring, executes SHM with an amplitude A1A_1. When this mass passes through its mean position, then a smaller mass of 124 g is placed over it and both masses move together with amplitude A2A_2. If the ratio A1A2\dfrac{A_1}{A_2} is αα−1\dfrac\alpha{\alpha-1}, then the value of α\alpha will be ______.

Answer and worked solution

Official answer: 16

At the mean position momentum is conserved: 0.9v1=1.024v20.9v_1=1.024v_2.

Amplitude A=vω=vmkA=\frac v\omega=v\sqrt{\frac mk}, so A1A2=1.0240.9=1615=αα−1\frac{A_1}{A_2}=\sqrt{\frac{1.024}{0.9}}=\frac{16}{15}=\frac\alpha{\alpha-1}.

Answer: 16