This topic can be found in your textbook on pp. 48-52 Acceleration This topic can be found in your textbook on pp. 48-52 Vocabulary: acceleration rate “In the Car” (1963) Roy Lichtenstein

What do you think? What is acceleration? Write down your own definition from your experience. Share your answer with your neighbor and see if you can refine your definition. Now share your refined answer with another group and see if you can refine it even more.

What do you think? Based on your definition of acceleration, are any of the following cars accelerating? a. A car shortly after a stoplight turns green b. A car approaching a red light c. A car with the cruise control set at 80 km/h d. A car turning a curve at a constant speed e. A car crashing into a tree f. A car rolling down a hill without brakes Do you think you need to modify your definition after thinking about any of these situations? Why or why not?

Acceleration Definition: The rate of change of velocity. How does this compare to your definition? (BTW: What does “rate” mean again?)

What do you think? What evidence do you have that the car below is accelerating? (Each picture was taken at 1 second intervals.) 0s 1s 2s 3s 4s

What do you think? Because the car has travelled a greater distance each second, it must have a greater velocity each second. By definition it is accelerating because the car is changing velocity. 0 s 1 s 2 s 3 s

Acceleration due to Gravity Once again you can see the effects of acceleration using stop motion photography.

Acceleration Mathematically Since acceleration is the rate of change in velocity, acceleration can be calculated using the following equation: 𝑎= ∆𝑣 ∆𝑡 or 𝑎= 𝑣 𝑓 − 𝑣 𝑖 ∆𝑡 SI Units: 𝑚/𝑠 𝑠 or m/s2

Important points: Acceleration is a vector (it has both magnitude and direction), so… Speeding up is acceleration Slowing down is acceleration Changing direction is acceleration

Think about the following scenarios Think about the following scenarios. What will the sign of the acceleration be? Initial Motion Change in Motion Sign of Acceleration Moving forward (+ direction) Speeds up positive Slows down negative Moving backward (- direction) No change in motion no acceleration

Math Practice Find the acceleration of an amusement park ride that falls from rest and reaches a velocity of 23 m/s downward in 3.0 s. Answer: -7.7 m/s2

Math Practice If a car traveling at 5.67 m/s speeds up over 15.0 s with a constant acceleration of 2.3 m/s2, what is the car’s final acceleration?

Acceleration Summary Equation Summary 𝑎= 𝑣 𝑓 − 𝑣 𝑖 ∆𝑡 Measurement Symbol SI Unit acceleration a m/s2 Equation Summary 𝑎= 𝑣 𝑓 − 𝑣 𝑖 ∆𝑡