One-Dimensional Motion
When you drop an object, it falls vertically toward the center of the earth due to the constant acceleration of gravity.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"OpenStax College, College Physics. October 19, 2012."
http://cnx.org/content/m42102/latest/?collection=col11406/1.7
OpenStax CNX
CC BY 3.0.