Calculating the speed of the tip of the hour hand

Question

I am totally confused on how to calculate this. The whole entire question is: A hour hand is 20cm long. The speed of the hour hand tip is ________m/s. No other info other than that. Anyone help?

Answer 1

You can calculate exactly what the disatance the tip travels in 12 hours (hint: it travels the whole circle).

The speed is simply distance (which you can calculate) divided by time (which you know is 12 hours).

Answer 2

This is just circular motion its easier than you think! For something moving in a circle the speed at any radius $r$ is given by $v=\frac{2\pi r}{t}$. So $20$cm in meters is $0.2$ and the time for it do to one revolution is $3600\times12$ seconds as it takes $12$ hours for one full revolution and that takes $12$ hours or $43200$ seconds!

So $v=\frac{2\pi \times 0.2}{3600\times 12}$

Roughly $0.00003$ meters per second!