Chapter 3 Objectives: 1) Define acceleration. 2) Relate velocity, time, and acceleration in equation form. 3) Know the units for acceleration. 4) Distinguish between (+) and (-) acceleration. 5) Be able to explain acceleration from a velocity versus time graph.

6) Collect the necessary data on a moving object in order to create a velocity versus time graph. 7) Determine and apply mathematical relationships among position, time, velocity, and acceleration. 8) Define Free-Fall. 9) Know the acceleration due to gravity for a freely falling object. 10) Solve problems involving objects in free-fall.

Chapter 3: Accelerated Motion I) Acceleration A) Defining Acceleration 1) _ _ _ _ _ _ _ _ _ _ _ _ : the rate at which an object’s velocity changes.

2) The Equation: 3) The Units:

4) (+) and (-) acceleration * If vf > vi then: * If vf < vi then:

5) Sample Problem: A car’s velocity decreases from 33. 0 m/s to 20 5) Sample Problem: A car’s velocity decreases from 33.0 m/s to 20.0 m/s in a time of 2.50 s. What was the car’s acceleration?

B) Determining Acceleration from a “Velocity vs. time” Graph:

II) Motion with Constant Acceleration A) Velocity with Average Acceleration:

B) Position with Constant Acceleration:

C) An Alternative Expression:

D) Put Them All Together:

E) Example problem: Page 69, #29)   “A bike rider pedals with constant acceleration to reach a velocity of 7.5 m/s over a time of 4.5 s. During the period of acceleration, the bike’s displacement is 19 m. What was the initial velocity of the bike?”

* The coin and feather demonstration! III) Free Fall   ·        _ _ _ _ _ _ _ _ : An object falling without air resistance; only experiences gravity. * The coin and feather demonstration!

A) Acceleration Due to Gravity (g) 1) The acceleration due to gravity is the acceleration of an object in free fall. 2) The value for g:

3) The Concept:

1)     4) Objects dropped straight down: a) The Equations (modified):

b) Sample Problem: “A flower pot falls from the window of a fifth floor apartment 15.0 m above the sidewalk.” a) How long does it take the flower pot to hit the sidewalk below?

b) What is the velocity of the flower pot as it hits the sidewalk?

5) What Goes Up, must come Down:

a) Sample Problem: “A football punter kicks the football straight up into the air. If the football falls back and hits the punter on his head after 4.0 s, what was the initial velocity of the football?”