1. Aim: How do we represent 1-D motion?
Do Now: Quiz
HW: Problem Set

2. How can determine the velocity of an object?
Speed- Distance/Time
Velocity- Displacement/Time
Velocity has magnitude and direction, so it’s a vector.
Speed only has Magnitude.

3. Position vs. Time Graph for a hockey puck gliding over ice
What is the puck’s position at 3 seconds?
What is the puck’s average velocity from 0s-7s?
Why is the puck’s velocity constant?

4. How do we graph acceleration?
This is when an object picks up speed (speeds up)
Which graph shows an object accelerating? How do you know?

5. How do we determine an objects acceleration?
Based on the slope from the graph…
What is the formula for acceleration? OR

6. Instantaneous vs. Average
Go to your assigned station and describe each term given.

7. Average Speed is the distance traveled divided by the elapsed time or time interval. V = Δx/Δt
Instantaneous velocity has the same magnitude as instantaneous speed and is described as average velocity taken over an infinitesimally small time.
Average Acceleration is the change in velocity per unit time. a = ΔV/Δt
Instantaneous Acceleration: Average acceleration taken over an infinitesimally short time period.
Drive around car as example.

8. Rabbit in a rabbit hole…
a. What is the rabbits instantaneous velocity at t=10s?
Lets look at the slope tangent this point…
V = (3-0)m/(10-0)s = 0.3 m/s
How about t = 30 sec?

9. Average velocity
What is the rabbits average velocity between t=0 and t=5s?
Lets look at the slope between these points…
Vavg = (1.5-0)m/(5-0)s = 0.3m/s
How about between t=25s and t=30s?
Vavg = (16m-9m)/(30s-25s)
Vavg = 1.4 m/s
How about t=40s to t=50s?

10. Physics Taboo
Play physics taboo where you must describe the graph without using any defining phrases from physics.
OFF LIMITS:
velocity
acceleration
positive
negative
increase
decrease it
object
constant

11. Physics Taboo!!! OFF LIMITS: velocity acceleration positive negative
increase
decrease it
object
constant

12. Physics Taboo!!!

13. Velocity vs. Time graphs
What can we determine from the graph?
Slope = acceleration
When crossing the x-axis, the object changes direction.
How is velocity at these two places the same, but different?
It has the same magnitude, but different direction!

14. Physics Taboo! OFF LIMITS: velocity acceleration positive negative
increase
decrease it
object
constant

15. Example: Question 50, Ch. 2 Giancolli
Taking slope: V = (3-0)m/(10-0)s = 0.3 m/s
(22-8)m/(35-25)s = 1.4 m/s
Vavg = (1.5-0)m/(5-0)s = 0.3 m/s
Vavg = 1.4 m/s
Vavg = m/s