1. BELLWORK : What does it mean to be fluid?
Fluids
BELLWORK : What does it mean to be fluid?

2. Bellwork – 01/24/17
You are on an ice-covered pond and the ice starts to crack – what do you do?

3. Bellwork – 02/01/16 On ice and it starts to crack – what do you do?
Lay down flat
Distributes weight over more surface area

4. BELLWORK - Pressure
What is pressure?

5. TN Standards
CLE – Investigate relationships among the pressure, temperature, and volume of gases / liquids
CLE.3202.Inq.3 – Use appropriate tools and technology to collect precise and accurate data
CLE.3202.Inq.6 – Communicate and defend scientific findings

6. Pressure [ Chpt 3 – section 3 ]
What is pressure?
Feeling forced to do something
A force needed to squash an object
Force exerted per unit area of contact

7. PhET simulation Heat water to steam ( turn heat up at bottom )
What happened to pressure in a closed container?
So why does the container ‘splode??

8. Balloons
While it is running, we’ll use balloons as an example of pressure
How does amount of gas in balloon relate to its size?

9. Balloons
What direction is the gas inside the balloon pointing to?

10. Balloons
What direction is the gas inside the balloon pointing to if really hot?

11. Balloons
What can we say about the pressure found in balloons of different sizes? ( start out the same size )
Small one
Big one

12. Balloons
What can we say about the pressure found in balloons of different sizes? ( start out the same size )
Small one
Big one
PRESSURE IS LARGER IN THE BIGGER ONE

13. Challenge What is a possible mathematical relationship for pressure?
Force and surface area are involved
What are independent and dependent variables?

14. Pressure Force exerted per unit area of a surface
Pressure = F / A ( force divided by area )

15. Pressure - Example Write down or Estimate your weight in lbs :
Estimate the area of your shoe-sole ( in2 ):
x “ wide & y “ long
Shoe area =
Pressure when standing on floor equals:
Weight / total shoe-area

16. Pressure - Example Write down or Estimate your weight in lbs :
Estimate the area of your shoe-sole ( in2 ):
Mine – 4.25 “ wide & 12 “ long
Shoe area = 51 x 2 = 102 in2
Pressure when standing on floor equals:
Weight / total shoe-area
1.9 psi exerted on floor

17. Pressure – Math Relationships
Force is directly proportional and surface area of ( contact ) is inversely proportional to pressure
P = F / A
Increase force  increase pressure
Increase area  DECREASE pressure

18. Buoyant Force A buoyant force pushes the boat up
All fluids exert an upward buoyant force on matter

19. Buoyant Force
Archimedes’ principle states that an object floats if the buoyant force on the object is equal to the object’s weight
An object’s ability to float is based on the buoyant force, density of the fluid, and the density of the object

20. Hydrostatic Pressure
Pressure felt by a column of fluid ( so, just being under a certain amount of fluid )
Does not matter how much volume of fluid there is – ONLY the depth
Pressure = fluid density * gravity * depth

21. Pascal’s Principle
An enclosed fluid exerts pressure equally in all directions
A change in the external pressure exerted on an enclosed fluid is transmitted equally and unchanged in all directions ( every point ) within that fluid

22. Work with Partners
Study Guides
Pg 12
#2, 3 ( put in N / cm2 )

23. Challenge / Exit Pass Consider a submarine at the bottom of the ocean.
What is the water doing to the submarine
Why does the submarine not get crushed?

24. PLC Day / Upcoming in Week
Gonna watch stuff ‘splode ??
Open-Notes Quiz Thursday/Friday

25. Exit Pass