Acceleration

What is Acceleration? A measure of the change in velocity during a period of time An object accelerates when: its velocity changes (increasing/decreasing speed or changing direction) So changing speed or direction

Another Way of Saying Acceleration The rate at which velocity changes

Examples of Acceleration On a roller coaster – as it changes speed and direction In a car when you hit the gas In a car when you slam on the brakes!

Can You Feel Acceleration? Yes! You can feel acceleration in a car push you forward, backward, or side to side. This is due to the rate of change in velocity (acceleration)

What If? YES! This is a change in velocity! When a car slows down is it accelerating? YES! This is a change in velocity!

Representing Acceleration Just like velocity, acceleration has a direction This is represented by an arrow

Speeding Up Final velocity longer arrow Acceleration points forwards

Slowing Down Final velocity shorter arrow Acceleration points backwards

Changing Direction Following the velocity arrows, we see that the change in direction is toward the inside of the curve

Average Acceleration vf Final Velocity vi Initial Velocity t Time a Acceleration

Average Acceleration Problem A bicyclist started from rest along a straight path. After 2.0s his speed was 2.0m/s. After 5.0s his speed was 8.0m/s. What was his average acceleration? Initial Speed? Final Speed? Total Time?

Average Acceleration Problem A bicyclist started from rest along a straight path. After 2.0s his speed was 2.0m/s. After 5.0s his speed was 8.0m/s. What was his average acceleration? 2.0 m/s2

Why m/s2 Because acceleration is the meters per second… per second So we square the seconds instead of saying m/s*s

How to do it! How to do acceleration problems! Khan Academy Acceleration Problem

Practice Textbook pg. 33 #1-4