# Acceleration- Change in Velocity occurs when an object _____________________ occurs when an object ______________ in speed. occurs when an object __________.

## Presentation on theme: "Acceleration- Change in Velocity occurs when an object _____________________ occurs when an object ______________ in speed. occurs when an object __________."— Presentation transcript:

Acceleration- Change in Velocity occurs when an object _____________________ occurs when an object ______________ in speed. occurs when an object __________ in speed. increases decreases changes direction.

Types of acceleration Increasing speed – Example: Car speeds up at green light Decreasing speed – Example: Car slows down at stop light Changing Direction – Example: Car turns screeeeech

Question 1 How can a car be accelerating if its speed is a constant 65 km/h? A car is accelerating if it is changing directions.

Calculating Acceleration Acceleration = Final speed – Initial speed Change in Time

Calculating Acceleration 0 s 1 s2 s3 s4 s 0 m/s 4 m/s 8 m/s 12 m/s16 m/s Acceleration = 16m/s - 0m/s 4s Acceleration =4 m/s 2

Question 2 A motor cycle accelerates from 20 m/s to 40 m/s in 2 seconds. What is the rider’s average acceleration? a = 40m/s – 20m/s 2s a = 20m/s 2s a = 10m/s 2

Graphing Acceleration Can use 2 kinds of graphs – Speed vs. time – Distance vs. time

Graphing Acceleration: Speed vs. Time Graphs Speed is increasing with time = accelerating Line is straight = acceleration is constant

Graphing Acceleration: Speed vs. Time Graphs In Speed vs. Time graphs: Acceleration = Rise/Run Run = 4 s Rise = 2 m a = 4 m/s ÷ 2 s a = = 2 m/s 2

Graphing Acceleration: Distance vs. Time Graphs Curved line means the object is accelerating. Your speed is increasing. Remember slope = speed.

Question 3 1) How is the speed of the car changing? (speeding up, slowing down, or staying the same) 2) What is this car’s acceleration? Run = 3 s Rise = -6 m/s The car is slowing down a = -6 m/s 3 s a = -2 m/s 2

Question 4 1)Which line(s) represents an object that is accelerating? 2) Which line(s) show positive acceleration? 3) Which line(s) show negative acceleration? 4) Which line(s) show constant acceleration? all of them green and black red and blue blue and green

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