2. Speeding Up and Slowing Down? 1-1-3 Acceleration

3. ACCELERATION –change in VELOCITY occuring over TIME –measured in METERS PER SECOND 2 –VECTOR Positive Velocity Positive Acceleration Speeding up in + direction Negative Velocity Negative Acceleration Speeding up in - direction Positive Velocity Negative Acceleration Slowing down Eventually speeds up in – direction! Negative Velocity Positive Acceleration Slowing down Eventually speeds up in + direction!

4. Equations “Acceleration is a rate of change in velocity” “The slope of a v-t graph tells what the ACCELERATION IS DOING!” “An object’s velocity at any point in time can be found by considering: - its starting velocity - its acceleration - the amount of time over which it accelerates”

5. Example Two cars start at the same point. Car A starts with a velocity of -5 meters per second while Car B starts with a velocity of +3 meters per second. At the end of 15 seconds car A has a velocity of +25 meters per second. v f = v i + at +25 m/s = -5 m/s + a(15 s) a = +2 m/s 2 v f = v i + at v f = +3 m/s + (+2 m/s 2 )(4.0 s) v f = +11 m/s –At what rate did car A accelerate?–If Car B has the same acceleration, what is its speed at the end of 4.0 seconds?