1. COACH O’ROURKE

2. Introduction Remember: velocity is __________________________ Acceleration is the rate of change in velocity So think back: which of the following are accelerating? What are the parts of a car that can be used to accelerate it? Gas pedal, brakes, and steering wheel speed with a direction

3. Acceleration Acceleration is any change in a state of motion. A car slowing down is still changing its motion, so it is still accelerating! We call it:_______________, or _________________ acceleration, but accelerating none-the-less! decelerationnegative

4. Formula Since acceleration is a rate, it must be: Divided by time! The formula for acceleration is: acceleration = __________________ OR acceleration = __________________ change in velocity time v final - v initial time

5. Units acceleration = v final – v initial time What are the units for velocity? meters per second, or m/s What are the units for time? seconds, or s So what are the units for velocity? acceleration = [m/s] = [m/s 2 ] [s]

6. Units practice Determine if the following quantities represent time, distance, velocity, or acceleration: 70 m 99 m/s up 51 s 920 m/s 2 east

7. When solving a Physics problem… Write out each step of GUFSA: Given Unknown Formula Steps Answer

8. Example problem: In 2.5 seconds, a car moving in a straight line increases its speed from 20 m/s to 25 m/s. What is its acceleration? Given: v final = 25 m/s v initial = 20 m/s time = 2.5 s Unknown: acceleration = ? Formula: acceleration = v final – v initial time Steps: acceleration = = 25 m/s – 20 m/s 2.5 s = 5 m/s 2.5 s Answer: acceleration = 2 m/s 2

9. Example Problem: Natalie accelerates her skateboard along a straight path westward from rest to a velocity of 4.0 m/s in 2 s. Find her average acceleration. Given: v final = 4.0 m/s v initial = 0 m/s time = 2 s Unknown: acceleration = ? Formula: acceleration = v final – v initial time Steps: acceleration = = 4.0 m/s – 0 m/s 2 s = 4 m/s 2 s Answer: acceleration = 2 m/s 2