How to Calculate Acceleration

If you happen to be taking introductory physics, the whole concept of acceleration may be something new to you. For instance, you might wonder how acceleration can be negative. Or you might not understand the meaning of the units m/s². Use the following steps to calculate and understand acceleration.

Instructions

Difficulty: Easy

1. Remember that acceleration is a change in velocity over time. Mathematically, this means that a = (final velocity - initial velocity) ÷ time elapsed.
2. Try a simple acceleration problem. Say that you're driving at an increasing speed. You notice that at the precise moment the clock turned to 2:02, your speedometer read 45 mph, and that after a minute had passed your speedometer read 55 mph. You can calculate your rate of acceleration (a) as 55 mph - 45 mph ÷ 1/60h.
3. Realize that the above example can only be used to calculate constant acceleration. That is, if your car at any time during that minute had stopped speeding up, the equation wouldn't work.
4. Understand that the formula for acceleration is the mathematical description of a curve. This is why acceleration can be negative; if the trajectory is in the opposite direction or if it is downward it falls into the negative portions of the graph.

Tips & Warnings

• The units m/s² (that is, meters per second squared) are simply the units of velocity (m/s) over the unit for time (s), m/s/s. It's perfectly acceptable to use other measurements of velocity and time to calculate acceleration as in the example above that used miles and hours; just be sure to use the same time unit in the top and bottom of the equation.