If you have a rhotic accent, you pronounce the /r/ sound whenever the letter 'r' appears in a word, like in 'learn', 'better' and 'perfect'. North American accents are usually rhotic, and other ...

(This area is also called the equator.) If you estimate that a day is 24 hours long, you divide the circumference by the length of the day. This produces a speed at the equator of about 1,037 mph ...