Wednesday, 22 December 2010
Written by David Chandler
Galileo was the first to describe the amazing fact that, apart from air resistance, all objects fall at the same "rate." If you have not experienced this fact directly, try dropping a large rock and a pebble side-by- side. The rate we are referring to is not a "speed," because for a falling object the speed is constantly changing. The rate we are talking about is actually the "rate of increase of speed," how quickly the speed builds up, called acceleration. The acceleration achieved by all falling bodies, apart from air resistance, is called the "acceleration of gravity."
Gravity causes freely falling objects to increase their speed by about 32 ft/s per second. (The awkward unit, feet per second per second is commonly abbreviated ft/s2.) When an object is dropped, the speed is initially zero, but it immediately starts speeding up. After 1 second its speed will be 32 ft/s. After 2 seconds its speed will be 64 ft/s. Etc. 32 ft/s2 is an approximation. The "acceleration of gravity" actually varies slightly from place to place. In New York City it is 32.159 ft/s2.
Read the entire article
No comments:
Post a Comment