AIIMS2018Physics-Kinematics

AIIMS 2018 Physics Equations of Motion MCQ Question

Type: MCQ-numerical-Medium-Class 11

Given equation of motion is, x = 8 + 12t - t³. The expression of velocity is, v = dx/dt = 0 + 12 - 3t². The velocity will be zero at 12 - 3t² = 0 ⇒ t = 2 sec. The acceleration is a = dv/dt = 0 - 6t. At t = 2 sec, the acceleration is aₜ₌₂ = -6(2) = -12 m/s². Thus, the retardation is 12 m/s².

Correct Answer

Option D

Detailed Explanation

The calculation shows that at t=2t = 2 seconds, the velocity vv becomes zero, indicating that the object has come to a stop. The acceleration at this moment is a=12m/s2a = -12 \, \text{m/s}^2, which signifies that the object is experiencing retardation (deceleration) as it slows down. Since the problem explicitly states that the retardation is 12m/s212 \, \text{m/s}^2, option D correctly reflects this value. Other options are not applicable as they do not provide relevant information or values related to the problem.

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