Pronunciation: /ækˌsɛləˈreɪ ʃən/ ?

When a car accelerates, it changes speed.[1] If a car is going 20 kilometers per hour (kph), and it accelerates to 30 kph it has changed speed by 10 kph. Acceleration is measured in units change in speed (velocity) per unit of time.

Graph of accelerate. At time=0, speed=50 meter per second. At time = 10s, speed = 60 meters per second.
Figure 1: Acceleration

If, at a point in time, an object is going 50 meters per second (mps) and 10 seconds later it is going 60 mps, the object's average acceleration is

(60 m/s - 50 m/s) / 10 s = 10 m/s / 10 s = 1 m/s^2.
1 m/s2 is read as, "One meter per second squared".

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Manipulative 1: Acceleration. Created with GeoGebra.

Take an object is going 70 kph and 10 seconds later it is going 100 kph. Since hours is not the same unit of measure as seconds, one must first change the 10 seconds to hours:

10 seconds*(1 minute/60 seconds)*(1 hour/60 minutes)=(10*1*1 hours)/(3600)=(1/360)hours.

So the acceleration is

(100mph - 70mph) / (1 / 360 ) hours = 30 mph * 360 1/hours = 1080 m/h^2.

Acceleration is measured using a unit of speed or velocity divided by a unit of time. Speed is measured in distance divided by time. Putting these together, speed can be measures in unit of distance divided by unit of time squared. Some of the commonly used measures of acceleration are:

AbbreviationUnit of measure
m/h2kilometers per hour squared
k/h2kilometers per hour squared
m/s2meters per second squared
Table 1: Units of Measure of Acceleration


  1. acceleration. WordNet. Princeton University. (Accessed: 2011-01-08).

More Information

  • McAdams, David. Velocity. All Math Words Encyclopedia. Life is a Story Problem LLC. 2009-03-12.
  • McAdams, David. Length. All Math Words Encyclopedia. Life is a Story Problem LLC. 2009-03-12.

Cite this article as:

Acceleration. 2009-12-24. All Math Words Encyclopedia. Life is a Story Problem LLC.


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Revision History

2009-12-24: Added "References" (McAdams, David.)
2008-12-13: Simplified wording (McAdams, David.)
2008-10-05: Expanded 'More Information' (McAdams, David.)
2008-09-16: Corrected math error (McAdams, David.)
2008-06-07: Corrected spelling errors (McAdams, David.)
2008-04-16: Initial version (McAdams, David.)

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