Engineering Board Exam Reviewer · Rectilinear Motion: Velocity and Acceleration · medium
A particle's position is s=t3-9t2+24t. At what times is it momentarily at rest?
- t=1 and t=3
- t=3 only
- t=2 and t=6
- t=2 and t=4
Answer
D. t=2 and t=4
Solution
v=3t2-18t+24=3(t-2)(t-4)=0 t=2 or t=4.
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