MixedMediumQuestion 310015
Question
A particle moves with displacement s = t³ − 6t² + 9t. The particle is at rest when t equals:
- A1 and 3Correct
- B0 and 6
- C3 only
- D1 only
Correct answer
1 and 3
Explanation
Velocity v = ds/dt = 3t² − 12t + 9 = 3(t²−4t+3) = 3(t−1)(t−3). v = 0 at t = 1 and t = 3.