Definition: AccelerationVector quantity:

magnitude (value) & directionRate at which an object changes

its velocity. “How fast an object is getting faster”

If the velocity of an object is

changing, it is accelerating!

Definition: Acceleration“How fast an object is getting faster”Every second,

object goes 10 m/s faster to the north

Units are:Meters per second per secondm/s/s

Equation: Acceleration

a =

Animation: AccelerationPhysics Classroom: Acceleration Animation

Constant AccelerationVelocity changes by a constant amount each

second.The magnitude can change. (How fast it is

going)And/or…. The direction can change.

An object with a constant velocity is not accelerating. 

In this class, ALL acceleration will be constant.

Accelerating Objects Are Changing Their Velocity

Equation: Acceleration

= A car goes from 0 m/s to 40 m/s in 10 seconds.

What is the acceleration of the car?Accel = = = = 4 m/s /s

Acceleration =Velocity(final) - Velocity(original)

time

A car traveling at 60 mph accelerates to 90 mph in 3 seconds. What is the car’s acceleration?

=90 mph - 60 mph

3 seconds

=30 mph

3 seconds

= 10 mph/second

Study in AccelerationRocket Sled

Graphing: AccelerationPosition vs.

TimeVelocity vs.

TimeAccel. vs.

Time

Slope of x vs. t =

velocity

Slope of v vs. t =

acceleration

Graphing: Acceleration

Change in Velocity

- Speed vs Time Graph: Constant

acceleration produces a straight line (linear slope,

rise/run

a = v/t

Free fallThe constant

acceleration of an object moving only under the force of gravity (g).

The acceleration caused by gravity is 10 m/s2

If there was no air, all objects would fall at the same speed

Doesn’t depend on massAfter 1 second falling at

10 m/sAfter 2 seconds 20 m/s3 seconds 30 m/s

FallingAir resistance will

increase as it falls faster

An upward force on the object

Eventually gravity will balance with air resistance

Reaches terminal velocity - highest speed reached by a falling object.

Terminal velocityForce of gravity is constant

air resistance increases as you speed up

until the force is equal

Equal forces, no acceleration

constant velocity terminal velocity

Balloon RacersWhat will happen if I let go of the blown up

balloon?Why did that happen?How can we measure the speed, distance or

acceleration of the balloon?A track?Attach the balloon to something?