NECO 2024 · Paper 1 · Q58

A particle moves a distance of SS metres in tt seconds, where S=5t3−12t2+7S = 5t^3 - 12t^2 + 7. At what time is its acceleration zero?

Worked solution (try it first)
  1. Velocity is v=dSdt=15t2−24tv = \frac{dS}{dt} = 15t^2 - 24t.
  2. Acceleration is a=dvdt=30t−24a = \frac{dv}{dt} = 30t - 24.
  3. Set a=0a = 0: 30t=2430t = 24, so t=0.8t = 0.8 s, option A.

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