Acceleration measures the change in a body's speed over time. The most common method of calculating it therefore involves directly finding the change in velocity, by subtracting the initial speed from the final one, and dividing the result by the length of time that the acceleration takes. If you don't know an object's change in velocity, however, another method of calculating its acceleration exists. A body's acceleration is inversely proportional to its mass at a constant force.

Subtract the angle between the force and the direction of acceleration from 90. If the force acts in the same direction as the object moves, this angle is 0  90  0 = 90.

Find the sine of this difference. If you don't have a scientific calculator see Resources. With this example, sin(90) = 1.

Multiply this answer by the amount of force that acts on the object. If, for instance, 100 Newtons act on the object then 100 x 1 = 100.

Divide this answer by the object's mass. If it has a mass, for instance, of 20 kg then 100 ÷ 20 = 5. This is the object's acceleration, measured in meters per second squared.
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