 ###### Matt Jones

M.Ed., George Washington University
Dept. chair at a high school

Matt is currently the department chair at a high school in San Francisco. In his spare time, Matt enjoys spending time outdoors with his wife and two kids.

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# Acceleration

Matt Jones ###### Matt Jones

M.Ed., George Washington University
Dept. chair at a high school

Matt is currently the department chair at a high school in San Francisco. In his spare time, Matt enjoys spending time outdoors with his wife and two kids.

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The acceleration of an object is the change in its velocity over a period of time, or the rate at which its velocity increases. The units for acceleration are distance/time^2 (for example m/s^2).

Okay let's talk about acceleration. You've all heard about acceleration when you watch a car advertisement, this car goes 0 to 60 in 5.2 seconds. What they're really telling you how well that car accelerates. So acceleration is the rate of change of velocity, how quickly it can get from a low speed 0 to a very high speed okay?

So let's first look at the units because the units for acceleration can often times be confusing okay? So we have the rate of change of velocity so we have a final velocity minus an initial velocity over time okay? Now remember velocity is like like meters per second it's a distance over time, so if you have a distance over time minus the distance over time we end up with distance over time divided by time, so what we're going to do is we're going to move both of our time units down to the denominator and we're going to have a distance over time squared okay? So let's look at an example of how we could solve an acceleration problem okay? Like that car that was accelerating, how fast was that rate of acceleration okay? So let's say that car goes from 0 kilometers per hour to 100 kilometers per hour in 10 seconds okay? I need to take my final velocity 100 kilometers an hour minus my initial velocity 0 kilometers an hour, remember to include your units, sometimes you can get confused if you drop your units and you don't know what you're talking about okay? So we've got that over 10 seconds okay? Now notice I have seconds here and hours here, is that a problem? No it's not, we can actually use units where we have hours, second hours or hours seconds those are fine okay? So when we solve that 100-0 is a 100 divided by ten equals 10 kilometers per hour second okay? So that is our rate of acceleration 10 kilometers per hour second.

One final note about acceleration, remember we're talking about changes in velocity and velocity involves not only a distance over time but in direction so we have going the same speed but we're changing direction our velocity is changing and our acceleration will be accelerating as we go around the curve so it's not just accelerating going straight we can also as we turn keeping the same velocity we can also accelerate even our speed remains the same and that's important to remember that acceleration.