This was a question from a Unit 1 physics paper. I reaaaallly don't understand how we'd attempt this!!!
In the eighteenth century, James Watt manufactured steam engines. He needed a way to demonstrate the benefits of these compared to the horses they replaced. He did some calculations based on horses walking in circles to turn a mill wheel. Watt observed that a horse could turn the wheel 144 times in one hour. The horse travelled in a circle of radius 3.7 m and exerted a force of 800 N. Show that the work done by the horse in turning the wheel through one revolution was about 20 000 J.