Deceleration, or decrease in speed, can be calculated using multiple different formulas, depending on the available parameters. Some deceleration formulas include a = (v  u)/t, and a = (v^2  u^2) / (2s).
One formula to calculate deceleration is a = (v  u)/t, where a is the deceleration, v is the final velocity, u is initial velocity and t is the time taken. If distance covered is known but time passed is not known, a second formula that can be used is a = (v^2  u^2) / (2s), where a is the deceleration, v is final velocity, u is initial velocity and s is the distance covered. The deceleration formulas calculate the rate of decrease in overall speed. Deceleration is typically measured in meters per second^2, or other distance per time unit squared units.
(Final Velocity Initial Velocity)/ Time It's the same as for acceleration.
http://wiki.answers.com/Q/What_is_the_formula_to_c...

1. Subtract the ending speed from the starting speed. 2. Convert the speed difference to units of speed that are compatible with the acceleration you will calculate. Acceleration
http://www.ehow.com/how_6081657_calculatedecelera...

First, convert your height to inches. Multiply your height by each other. Divide your weight by 4900. Multiply that number by 703 and that is your body mass index. For more information
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The formula for it is Deceleration=original velocityfinal velocity)/Time.
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