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# I need help with these word problems

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1.  A flywheel is rotating at 7 rad/sec.  It has a 15-cm diameter.  What is the speed of a point on its rim, in cm/min?

3. What is the angular speed in radians/second associated with a rotating an angle 3pi/4 radians in 2 seconds?

Mar 26, 2019

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1)
$$\omega = 7rad/s\\ r=15cm\\ v_{tan}=\omega r\\ v_{tan}= 7rad/s*(15cm)=105cm/s*(60s/1min)=6300cm/min$$
3)
$$\Delta \theta=\frac{3\pi}{4}rads\\ t=2s\\ \omega = \frac{\Delta \theta}{t}=\frac{\frac{3\pi}{4}rads}{2s}=\frac{3\pi}{8}rad/s$$

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Mar 26, 2019