1. Lets Start Off Today is a GREAT day for physics. But then again…
Any HW questions that you want answered before we go into the meat and potatoes of today?

2. FIRST ATTEMPT
You walk 8 steps forward, then 2 steps backwards, then 3 steps forward.
a) What is your displacement from the start after the 3rd segment?
Final position: 9 steps. Starting position: 0 steps. So displacement is (9-0) = 9 steps. (+ or forward)
b) What is your distance traveled from the start after the 3rd segment?
( ) = 13 steps.
c) What is your displacement in the 2nd segment?
Final position: 6 steps. Starting position: 8 steps. So displacement is (6-8) = -2 steps. Or 2 steps backwards

3. Back To Knowledge
Distance (not used that much in physics) is the overall amount traveled.
Displacement (used a lot in physics) is how far from a given point you are.
Displacement: Symbol: d, Unit: meters (m)
Direction matters! Left/West is -, Down/South is –
d=Δx, where x is position in meters, and delta is change (Xfinal-Xinitial)
Walking demonstration….

4. Definition of Velocity
Velocity is displacement over time
So ∆x/t
The net or overall velocity is overall ∆x/t
Since displacement involves direction, so does velocity

5. UNITS
DISPLACEMENT:
VELOCITY:

6. Lets Hear From The British
Lets see how to think of displacement and distance.

7. How does the overall displacement compare between the two?
They are the same due to same start and end point. Time does not matter. So both are ZERO.
How does the net velocity for each compare?
They are both zero for the net/overall race (As defined as d of race being from start point to end point).
How does the velocity after ten seconds compare for each?
Different! The plane has more velocity since it is further from the start after 10 seconds than the car.
Is there any point or time in this race where the car’s velocity is > the airplane’s velocity?
Yes! The first few moments of the race. The CAR was able to get to its max VELOCITY before the PLANE could. That idea is called……

8. 4 Questions to Answer
1) Does a car odometer show distance or displacement? Justify
2) Over the course of one full day, what is your displacement? Justify
3) Which is faster: -5m/s or +4m/s?
4) Can displacement ever be bigger than distance? Justify

9. I do
A person jogs sixteen complete laps around a quarter mile track in a total time of half an hour minutes at a constant velocity. Please calculate:
What is the average velocity in miles per hour?
ZERO!

10. ON THE BOARD
During a race, a Panda runs with a constant velocity of 10 m/s to the East.
A) What is the panda’s displacement after 6 seconds?
60m EAST
B) What is the panda’s acceleration?
0, because CONSTANT means not CHANGING!

11. ON THE BOARD
During a race, a Panda runs with a constant velocity of 10 m/s to the East.
A) What is the panda’s displacement after 6 seconds?
LETS DRAW A PICTURE/NUMBERLINE

12. So….. Constant velocity means….
There is no acceleration, the velocity remains the same value.

13. ON THE BOARD
A bus travels 60km south at a constant velocity of 40km/hr south. It then stops for 30 minutes. Then it travels 80km south at 60km/hr.
A) How many different ‘motions’ occurred here?
3…. South, None, South
B) Draw arrows with info to show them

14. ON THE BOARD
A bus travels 60km south at a constant velocity of 30km/hr south. It then stops for 30 minutes. Then it travels 80km south at 60km/hr.
C) How long did the total trip last in hours?
3.83 hrs

15. ON THE BOARD
A bus travels 60km south at a constant velocity of 40km/hr south. It then stops for 30 minutes. Then it travels 80km south at 60km/hr.
D) What was the average velocity for the entire trip? (km/hr)
Total disp/total time: 140 km/3.83 hrs =

16. You try supplement 1

18. You try supplement 2

20. To your seat temporarily
Acceleration: A change in velocity over time.
a = Δv/t , and Δv = vf – vi

21. Time to VOTE
A car is driving forward at a constant rate of 20 𝑚 𝑠 . Then the driver hits the gas and accelerates forward at 2 𝑚 𝑠 2 .
What would the cars velocity be after 4 seconds?

22. Time to VOTE
A car is driving forward at a constant rate of 20 𝑚 𝑠 . Instead, the driver hits the brakes and comes to a stop in 4 seconds.
What would the cars acceleration have to be for this to happen?