20 February 2013

Slow Derek

After watching this animation by Dan Ojari I am not sure I will ever read one of those little information cards that you get in cereal packets again. Ever.  This animation tells the story of Slow Derek who, as the name suggest, like to take things at an easy pace.  However, one morning he reads an interesting planetary fact – on one of those infocards – and Derek learns how quickly the earth rotates.  Things are never the same again for Derek, poor soul, who can’t quite compute his new knowledge.

Who can blame him for getting in to something of a tizzy?  After all, at the equator, the circumference of the Earth is 40,070 kilometers, and the day is 24 hours long so the speed is 1670 kilometers/hour ( 1070 miles/hr). This decreases by the cosine of your latitude so that at a latitude of 45 degrees, cos(45) = .707 and the speed is .707 x 1670 = 1180 kilometers/hr.  This formula can be used to find the speed of rotation at any latitude.  I think I will go and sit down for a while.