Velocity Acceleration Graphs Reference Points How do you

Velocity Acceleration Graphs

Reference Points • How do you know if you’re moving?

Speed Vs. Velocity • Distance divided by Time time • Units are distance/time • Also tells DIRECTION!

Do some math! Roni is biking 5 miles south and it takes her 30 minutes. What is her velocity? Sam is walking 2 miles to school, and it takes him an hour. What is his speed? Joe is driving for an hour, Debra runs a 6 minute and he goes 60 miles. mile. What is her speed? What was his speed?

Average Speed • Average speed is how far you went (TOTAL!) divided by how long it took you (TOTAL!) • Add up the TOTAL DISTANCE and divide by TOTAL TIME!

REVIEW: • A reference point is something you look at to see if you’re moving • Velocity is speed in a given direction • Average speed is total distance divided by total time

Acceleration • Acceleration is ANY change in VELOCITY – Acceleration – Decceleration – Changing direction (Centripedal Acceleration)

Acceleration Formula • Acceleration = Change in speed » CHANGE IN TIME » OR » Final velocity - Initial velocity » Time it took to change » *Why is it sometimes negative?

Do some math! Kendra’s car goes from 0 to 80 miles per hour in two minutes. What is her acceleration? As we took off, our airplane went 150 kilometers per hour. 1 hour later we were cruising at 975 kph. Jim’s bus slowed from 65 mph to 32 mph when he passed the school (3 minutes to slow). What’s his decceleration? My little brother takes 5 minutes to get up to 3 miles and hour on his tricycle. What’s his acceleration?

Review: • Acceleration is ANY change in velocity (even changing direction!) • Final velocity minus initial velocity divided by time it takes

Motion Graphs • Graph of SPEED has distance and time • Slope is SPEED • (rise = distance) • run time

Motion Graphs • Graph of ACCELERATION has speed and time • Slope is Acceleration • (rise = speed) • run time

Do these graphs say the same thing? • Top is a graph of SPEED • Bottom is a graph of ACCELERATION