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For a particle moving along x(t) = t³ − 3t² + 5, the velocity at t = 2 is:
A$0$ (incorrectly assumed at rest)
B$3$ m/s (omitted negative term)
C$2$ m/s (wrong calculation)
D$0$ m/s (3(4) − 6(2) = 0)
Answer & Solution
Correct answer: D. $0$ m/s (3(4) − 6(2) = 0)
v(t) = dx/dt = 3t² − 6t. At t = 2: v = 3(4) − 6(2) = 12 − 12 = 0. So at t = 2, the particle is instantaneously at rest. Could be turning point in motion.
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