This document discusses velocity, acceleration, and how to calculate them. It defines velocity as the rate of change of displacement and acceleration as the rate of change of velocity. It provides examples of positive and negative acceleration, such as speeding up or slowing down. The key formula for calculating acceleration is given as the change in velocity divided by the time taken, usually measured in meters per second squared. Examples are provided to demonstrate calculating average acceleration from changes in velocity over time.

1. Velocity and Acceleration 8SCIENCE Thurs. May 5/Fri. May 6

2. Review: Forces and Motion/Speed What is speed? Rate of change of a position How do you calculate average speed? Average speed = total distance time What is displacement? Change in position including a direction What is velocity? Rate of change of displacement

4. Acceleration Acceleration is the rate of change of velocity (speed with direction) Acceleration may be positive or negative:Positive – accelerates in the direction it is moving (speeds up) Ex: riding your bike forward and pedal harder to speed up Negative – accelerates in the opposite direction to its movement (slows down) Ex: riding your bike and pushing the brake slows you down

5. Positive and Negative Acceleration POSITIVE POSITIVE NEGATIVE

6. Calculating Acceleration Average acceleration (a) = change in velocity (v₂ - v₁) time (t) Usually in m/s² Example: If a student takes 2 s (seconds) to go from velocity of 0m/s to a velocity of 4m/s, what is the average acceleration? Example: If a car begins at a velocity of 2m/s and then speeds up to 18m/s over 4 s what is the average acceleration? Example: What does it mean if your acceleration is 0m/s? - This means you are not moving or that you are moving at a constant speed, and not speeding up/slowing down i.e. parked car, driving at a constant rate of 60km/h

7. Motion: Calculating Acceleration minilab pg. 152 Work with a partner. One of you should clap a slow, steady beat. The other partner should move along the taped course, stepping beside each line on the piece of tape. You should try and step beside each piece of tape on the beat of your partner’s claps. Create the table below to record information: Calculate the change in displacement (velocity) and the change in velocity (acceleration) for each time *Remember: velocity = displacement time Displacement = change in position Acceleration = final velocity – initial velocity time4) Experience negative acceleration by moving through the course from 3.6 – 0 while your partner claps a steady beat. QUESTION: As you move through the course forward and backward, does your velocity change?