The distance from the Earth to the Sun is 93 million miles. Assume: it takes 365 days for the Earth to travel once around the Sun and the Earth travels in a circle with the Sun at the centre. Work out the average speed of the Earth in miles per hour.

This question is testing your understanding of speed, distance and time and sounds much more complicated than it actually is. For a question like this one, it is best to draw a picture to help you get a better understanding of what is going on. The Earth is travelling in a circle around the sun. From the picture we have drawn, it is clear the radius of this circle is 93 million miles. For the Earth to travel once around the sun, it will have to travel around the circumference of this circle. Recall the equation of the circumference of a circle; 2pir. Hence, the distance travelled in one orbit of the sun is given by 2pi9310^6=18610^6pi miles. Remember, Speed=Distance/Time. The time we have for the Earth to travel this distance is 365 days. The answer must be in miles per hour, so convert the time into hours. 365 * 24 = 8760 hours. Now we can finally calculate the answer; 18610^6pi miles/8760 hours = 66705 miles per hour = 6.710^4 miles per hour.