Velocity

Explain why we say all 3 cars are changing their velocity

Sometimes we are interested in how fast the velocity of an object is changing

1) How fast is the car speeding up that is trying to pass me on the 2 lane road to Lubbock?

2) How fast did I slow down to avoid hitting the dog in the road?

3) How fast did the roller coaster go around the curve? b/c I am feeling sick!

Acceleration

Acceleration Definition: the rate at which velocity is changing

It can be a change in 1) velocity and/or 2) direction

Formula: Acceleration= velocity final – velocity initial time Unit: 10 m/s or m/s² s

Something to rememberA positive value for

acceleration shows speeding up

and negative value for acceleration shows slowing down

The correct terms are positive and negative acceleration

Let’s try a few for physics fun A softball player

increases her velocity from 2.0 m/s to 10.0 m/s in 3.0 seconds. What is her acceleration?

Problem #1 Looking forAcceleration

GivenVelocityinitial = 2.0 m/sVelocityfinal = 10.0

m/sTime = 3 seconds

Relationship

Problem #2 A car accelerates

at a rate of 3.0 m/s2. If its original speed is 8.0 m/s, how many seconds will it take the car to reach a final speed of 25.0 m/s?

Problem #2 Looking for Time GivenVelocitylinitial = 8.0

m/s; Velocityfinal = 25.0 m/s

Acceleration = 3.0 m/s2

Relationship