Projectile Motion

Pronunciation: /prəˈdʒɛk.taɪl ˈmoʊ.ʃən/ Explain

Projectile motion is the vertical motion of an object in a gravitational field given an initial velocity and height. The quadratic equation for projectile motion is:
where t represents time, a represents acceleration due to gravity, v0 represents the initial velocity, and h0 represents initial height. Since down is taken to be negative, acceleration due to gravity is a negative number.


Click on the blue points on the sliders and drag to change the figure.

What initial angle would make the projectile go only up or down?
Manipulative 1 - Projectile Motion Created with GeoGebra.


  1. Jeff is standing on top of 20 foot tower. He throws a stick down at an initial velocity of -10 ft/s. Use -32 ft/s2 for the acceleration due to gravity. What is the equation for the vertical height of the stick? At what time does the stick reach the ground?

    1Identify the values of the constants.
    2Plug the constants into the equation. Simplify the equation.
    3Set the height to zero.
    4Apply the quadratic formula.
    5Since a negative solution does not make sense in this problem, the negative solution is extraneous solution. Discard the extraneous solution.
    Example 1


  1. McAdams, David E.. All Math Words Dictionary, projectile motion. 2nd Classroom edition 20150108-4799968. pg 145. Life is a Story Problem LLC. January 8, 2015. Buy the book

Cite this article as:

McAdams, David E. Projectile Motion. 4/28/2019. All Math Words Encyclopedia. Life is a Story Problem LLC.

Image Credits

Revision History

4/28/2019: Changed equations and expressions to new format. (McAdams, David E.)
12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)
12/1/2018: Removed broken links, updated license, implemented new markup, updated geogebra app. (McAdams, David E.)
8/7/2018: Changed vocabulary links to WORDLINK format. (McAdams, David E.)
1/10/2009: Initial version. (McAdams, David E.)

All Math Words Encyclopedia is a service of Life is a Story Problem LLC.
Copyright © 2018 Life is a Story Problem LLC. All rights reserved.
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License