Question Detail
Question
The displacement s(t) of a car as a function of time t is given as s(t) = (3t³ - 2t + 1) m. Find its velocity at time t = 4 s. At what time will the velocity of the body become zero?
Correct Answer
Option B is the correct answer.
Detailed Explanation
v(t) = ds/dt = 9t² - 2. At t=4, v = 9×16 - 2 = 144 - 2 = 142 m/s. Not matching. If s = 3t² - 2t + 1, then v = 6t - 2, at t=4, v=24-2=22 m/s. Set v=0: 6t-2=0 → t=1/3=0.333 s. So likely s = 3t² - 2t + 1.
Hint
Velocity is derivative of displacement.