Rotational Motion Question 170
Question: The instantaneous angular position of a point on a rotating wheel is given by the equation$\theta (t)=2t^{3}-6t^{2}$ . The torque on the wheel becomes zero at
Options:
A) $t=1s$
B) $t=0.5s$
C) $t=0.25s$
D) $t=2s$
Show Answer
Answer:
Correct Answer: A
Solution:
[a] When angular acceleration
$\alpha $ is zero then torque on the wheel becomes zero.
$\theta (t)=2t^{3}-6t^{2}\Rightarrow \frac{d\theta }{dt}=6t^{2}-12t$
$\Rightarrow \alpha =\frac{d^{2}\theta }{dt^{2}}=12t-12=0\therefore t=1\sec .$
