A water wheel with diameter 3 m is used to measure the approximate speed of the water in a river. If the angular velocity of the wheel is 15 rpm, what is the speed of the river, in kilometres per hour?

linear velocity = circumferential distance*number of revolutions per minute so:

linear velocity = 15*pi*3 metres/minute = (15*pi*3/1000)*60 km/hour

You can crunch the numbers.

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Thanks Alan,

This would be a really nice one for Zac (or somene else) to explain in detail.

Where is Zac when we need him. Any other takers? LOL