Noah and Emma, track stars with superb hearing, ran as fast as they could to catch up to the ice cream truck in the next town over. They averaged 6 miles per hour, then rested to enjoy their ice cream. They averaged 4 miles per hour over the same distance on the way back. Not counting the time they rested, what was their average speed?
4.8 miles per hour. 5 mph is tempting, but incorrect. Pick any distance, say 12 miles there and 12 miles back. They take two hours to cover the first 12 miles and three hours to cover the return trip. In 5 hours they covered 24 miles which is an overall average of 4.8 miles per hour.
Hester goes out for an afternoon bicycle ride. She rides for one hour at five miles an hour, then three hours at four miles an hour and finally two hours at seven miles an hour. How many miles did she ride in total?
Second. Second place is next to winning. Seconds, the measure of time, pass quickly. Seconding a motion is requested by the chair of the body in Parliament. And the second place finisher in many sporting events such as the Olympics is awarded the silver medal.
And as for why the unit of time is called a second, it goes back to the days of Ptolemy. A second of time is the second small part, or pars minuta secunda, of an hour. (Thanks to Tim J for researching it).