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

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

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

BELLWORK - Pressure What is pressure?

TN Standards CLE.3202.1.8 – 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

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

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??

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?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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?

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

Exit Pass