1. Cornell Notes 2-5 Velocity and Acceleration
November 9, 2011
Pages 73 & 75

2. Velocity
Speed with direction is called velocity.

3. Constant Velocity
A plane with a constant velocity of 600 km/h west moves in a straight line. (Its speed and direction remain the same.)
A car going around a bend at a constant 30 mph has a constant speed, but its velocity is not constant. (Note the change in direction.)

4. Velocity
In other words. 500 mph is a speed. 500 mph NORTH is a velocity.
Speed
Velocity

5. Velocity You can change velocity in one of three ways. Speed up
Slow down (or stop)
Change direction

6. Acceleration
Just like speed and velocity are changes in position, acceleration is defined as a change in velocity.
An object with a positive acceleration is speeding up.
An object with a negative acceleration is slowing down.
If acceleration is Zero, then the object is keeping the same speed (and direction)

7. Calculating Acceleration
To calculate acceleration, you divide the change in velocity (speed) by the change in time.
a =
New Speed – Old Speed
Time
a =
v2–v1
t2–t1

8. Units of acceleration
To describe acceleration, scientists need one unit of distance and two units of time.
For example, a car that goes from 0-60 mph in three seconds has an acceleration of 20 miles per hour per second. (20 (mi/hr)/s)
In metrics this means you say “second” two times – like in 15 meters per second per second (15 (m/s)/s)
To make it easier, we instead say 15 meters per second squared (15 m/s2)