AIIMS2019Physics-Kinematics

AIIMS 2019 Physics Equations of Motion MCQ Question

Type: MCQ-numerical-Medium-Class 11

A body starts from rest with an acceleration a₁, after two seconds another body B starts from rest with an acceleration a₂. If they travel equal distance in fifth second, after the starts of A, the ratio a₁ : a₂ will be equal to

A

9 : 5

B

5 : 7

C

5 : 9

D

7 : 9

Correct Answer

Option C

Detailed Explanation

In this problem, we analyze the distances traveled by both bodies A and B during the fifth second of their motion. Body A, which starts first, covers a distance given by SA=12a1(t+2)212a1(t+1)2S_A = \frac{1}{2} a_1 (t + 2)^2 - \frac{1}{2} a_1 (t + 1)^2 for the fifth second, while body B, starting two seconds later, covers SB=12a2(t+1)212a2t2S_B = \frac{1}{2} a_2 (t + 1)^2 - \frac{1}{2} a_2 t^2. Setting these distances equal for the fifth second and simplifying leads to the ratio a1a2=59\frac{a_1}{a_2} = \frac{5}{9}, confirming option C as correct. Other options are incorrect as they do not satisfy the derived relationship between the accelerations based on the equal distances traveled in the specified time frame.

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