What is acceleration? – Probably heard it mean: “the process of speeding up” – More specifically: the rate at which velocity changes. Remember that velocity involves a change in either speed or direction.

Therefore, acceleration refers to increasing speed, decreasing speed, or changing direction. – Increasing speed What is a real world example of increasing speed? – Decreasing speed What is a real world example of decreasing speed? – Changing Direction So if a car has the same speed, if it goes around a curve it is accelerating (change in direction).

Try this on your own: – If a car can go from 0 to 60 meters per second in 5 seconds, what is the car’s acceleration? Final speed=60 meters/second Initial speed =0mph meters/second Time =5mph Therefore acceleration is (60 meters/second - 0 meters/second)/ 5secs= 12. – What is the unit on this number (Meters/second)/second= Meters/(second 2 ) =m/s 2

SI unit of acceleration is m/s 2 Try these problems by yourselves: – A roller coaster starts at 4m/s. Three seconds later its speed is 22 m/s. What is the average acceleration? (22-4)/3 = 6m/s 2 – If the roller coaster continues its current acceleration how fast will it be traveling in 3 seconds? Currently going 22 m/s. One second later it would increase by 6 m/s, going 28 m/s. So for each second it increases by 6 m/s. Therefore, after 3 seconds it will have increased by 18 (6*3), going 40 m/s (18+22).

How do we calculate acceleration? – To determine acceleration, you must calculate the change in speed per unit of time. – So acceleration= Final speed – Initial speed Time

When you have a graph (speed versus time), how is acceleration related to the line’s slope? – The slope= acceleration of an object.

Acceleration can also be seen on a distance vs. time graph. – The distance vs. time graph is not a straight line when the velocity is not constant. – This curved line indicates that the object is under acceleration.