Tick Tock!

Geometry Level 2

If the minute hand is 10cm long, then how fast is its tip moving?

20 π 20\pi cm/min 10 π 10\pi cm/min π 3 \displaystyle\frac{\pi}{3} cm/min π 6 \displaystyle\frac{\pi}{6} cm/min

Cristian Camilo Collazos by Cristian Camilo Collazos , 33, Canada

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1 solution

Eli Ross Staff
Sep 23, 2015

Every hour, the tip of the minute hand travels around a full circle (with radius 10 cm), so it travels 2 π r = 20 π 2\pi r = 20 \pi cm in 60 minutes. That's a speed of 20 π 60 = π 3 \frac{20\pi}{60} = \frac{\pi}{3} cm/min.

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