Acceleration - Physics answers questions


Tegla Loroupe, Kenyan runner

Acceleration is how much your speed changes in a certain amount of time.

Picture yourself standing in front of your house. When you stand still, your acceleration is zero. When you begin to walk, your speed is changing - that's what acceleration is - it measures how fast your speed is changing. If you begin by walking slowly, then gradually start to go a little faster, until after some time you are running, that's a slow acceleration. If you start running right away, going right from standing still to running, that's a fast acceleration.

People often mix up acceleration and speed, but they're not the same. Suppose you started out running, and then you kept on running at the same speed. Your acceleration would be zero - just like when you were standing still. You have acceleration only when you speed up or slow down, no matter how fast you are going. (Slowing down gives you negative acceleration, or deceleration).

You can use acceleration to find out the mass of an object, because force = mass x acceleration. This is how we find out the mass of other stars and planets far away from us.

Bibliography and further reading about acceleration:

Inclined Plane
Physics home

Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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