Acceleration  Acceleration= change in velocity overtime  Speeding up  Slowing down  Changing direction Formula Acceleration= final velocity – initial velocity = V f - V i time

Acceleration in a circular motion  Centripetal acceleration= acceleration that occurs in a circular motion (continuous acceleration)  Example: earth rotating

Deceleration  Deceleration= when you slow down or decrease your speed

Acceleration VS Deceleration ExampleHow velocity changesAcceleration or deceleration? Positive or negative answer? A plane taking off orIncrease in speedAccelerationPositive (+) A car stopping at a stop sign Decrease in speedDecelerationNegative (-)

Acceleration Practice Problem  Problem: A car accelerates from 0 miles per hour to 60 miles per hour in 5 seconds. What is its acceleration? Acceleration= ? Vf (final velocity)= 60 miles per hour Vi (initial velocity)= 0 miles per hour Time= 5 seconds Acceleration= Vf- Vi time Acceleration= 60 – 0 mph 5 seconds Acceleration= 12 mph/sec

Deceleration Practice Problem  Problem: A cheetah that is running at a constant speed of 60 km/hr is tackled in 9 seconds. What is its acceleration? Acceleration= ? Vf (final velocity)= 0 km per hour Vi (initial velocity)= 60 km per hour Time= 9 seconds * A NEGATIVE ANSWER= DECELERATION! Acceleration= Vf- Vi time Acceleration= 0 – 60 kph 9 seconds Acceleration= -6.7 kph/sec

Review Questions: 1.What is acceleration? 2.Does a change in direction affect acceleration?