STANDARD Physics Position and Speed MCQ Question
The position x of a particle with respect to time t along x-axis is given by x = 9t² − t³ where x is in metres and t is in second. What will be the position of this particle when it achieves maximum speed along the +x direction?
54m
81m
24m
32m
Correct Answer
Detailed Explanation
Given x = 9t² − t³, the speed v = dx/dt = 18t − 3t². For maximum speed, set dv/dt = 0, which gives t = 3 s. Substituting t = 3 s in x, x_max = 9 × 3² − 3³ = 54 m.
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