Question
A flywheel rotates with a uniform angular acceleration. Its angular velocity increases from $20\pi \, rad/s$ to $40\pi \,rad/s\,m\,10\,sec$ . How many rotations did it made in this period
✓
Answer
$\omega_{0}=20 \pi, \omega=40 \pi, \tau=10 \mathrm{s}$
$\omega=\omega_{0}+\alpha t$
$20 \pi=\alpha(10) \Rightarrow \alpha=2 \pi \mathrm{rad} / \mathrm{s}^{2}$
$\theta=20 \pi(10)+\frac{1}{2}(2 \pi)(10)^{2}$
$\theta=200 \pi+100 \pi$
$\theta=300 \pi$
$2 \mathrm{n} \pi=300 \pi$
$\mathrm{n}=150$ rounds
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