Chapter 10 Fluids

Intro.

Pascal

Archimedes

Bernoulli

Flow rate

Phases

Buoyancy

Gauges

Pressure

Density

barometers

Equation

**Phases of matter**

Gas

Liquid

Solid

compressible

Fills the container

Holds shape well

Not compressible

Fits shape of container.

Chapter 2-9

**Fluids**

**Density**

Density is an intrinsic property of a substance.

All similar substances have similar density.

Density is the measure of mass in a given volume

We use this a lot, especially

Which would have more

mass a solid piece of

copper or a solid piece of gold

A. Copper

B. Gold

C. Depends on volume of each

Units

Specific Gravity

no units

Pressure

This is the amount of force over a given area.

Units

Pascal's principle deals with

compression:

If I squeeze a balloon, the pressure

goes up,

not just where I squeeze it, but every

in a confined fluid.

**Pascal's Principle**

Written as:

A small mass on the smaller area, can lift a larger mass on the larger area.

Barometers work by Pascal's principle. It is also how we get 'mm mercury'.

**Buoyancy**

Things to note.

The buoyant force is different for each liquid you are in

It is equal to the weight of the displaced fluid

If an object is floating in the fluid, the weight of the displaced fluid is equal to the weight of the object.

Depth doesn't matter.

Show on board

Buoyancy teaches us that if all the ice

in the North pole glacier melted the ocean

would:

A. Rise and destroy coastal regions

B. Fall and create more beach front

C. Stay the same

2 key points (relating the object and the fluid)

Buoyancy and density are used together, often

If the object is floating, the masses are the same.

If the object is submerged the volumes are the same

**Fluids in motion**

Because we can't destroy or create mass there is an equation of continuity. Meaning the mass, or flow, is continuous.

In general if the fluid is allowed to have a changing density then we need to consider density, otherwise, the continuity equation is described by the

flow rate

equation.

**As the fluid moves through the larger area it moves slower, as it hits a narrower area it speeds up.**

If the flow rate in one section of

pipe is 15 m^3 / s, and then this pipe narrows

to a cross sectional area of 1.5 m^2. What is the

velocity of the fluid in this section?

A. 10 m/s

B. 15 m/s

C. 1.0 m/s

D. 0.1 m/s

E. 1.5 m/s

**Consider driving a car down a high way.**

Coming at you head on is a semi truck.

It passes you on your left, but a bit closer

than you might have liked.

What do you notice as you are passed by the truck?

Coming at you head on is a semi truck.

It passes you on your left, but a bit closer

than you might have liked.

What do you notice as you are passed by the truck?

**Bernoulli**

This is an example of Bernoulli's principle

Where velocity of a fluid is high, pressure is low

Where velocity of fluid is low, pressure is high

Bernoulli derived an equation that helps to

quantify his statement.

It is derived from a work, energy conservation

Thus there is a conserved quantity.

**Demo**

**Applications of Bernoulli principle**

ping pong ball

Car and truck

air plane wing

curve ball

etc.

ping pong ball

Car and truck

air plane wing

curve ball

etc.

**Bernoulli's principle is responsible for all the following except:**

A. Air planes lift

B. Smoke rising in chimneys

C. A curve ball

D. Mercury in a barometer

A. Air planes lift

B. Smoke rising in chimneys

C. A curve ball

D. Mercury in a barometer

**Example 12**

The maximum gauge pressure in hydraulic lift is 17.0 atm. What is the largest size vehicle (kg) it can lift if the diameter of the output line is 28.0 cm?

The maximum gauge pressure in hydraulic lift is 17.0 atm. What is the largest size vehicle (kg) it can lift if the diameter of the output line is 28.0 cm?

Example 29

An undersea research chamber is spherical with an external diameter of 5.20 m. the mass of the chamber when occupied is 74,400 kg. It is anchored to the sea bottom by a cable. What is (a) the buoyant force on the chamber, and (b) the tension in the cable?

**Example 41**

A 6.0 cm diameter horizontal pipe gradually narrows to 4.0 cm. When water flows through this pipe at a certain rate, the gauge pressure in these two sections is 32.0 kPa and 24.0 kPa, respectively. What is the volume rate of flow?

A 6.0 cm diameter horizontal pipe gradually narrows to 4.0 cm. When water flows through this pipe at a certain rate, the gauge pressure in these two sections is 32.0 kPa and 24.0 kPa, respectively. What is the volume rate of flow?

Gauge pressure

In my flat bicycle tire, what is the pressure?

Is it zero? (thus a vacuum)

Gauge pressure, is shifted by 1 atm

"To clarify, Archimedes' principle relates to buoyancy, Bernoulli's principle relates to water hoses, and Pascal's principle relates to hydraulics, correct?"

"Does Buoyancy increase as an object is submerged deeper in liquid? "

"Can you explain viscosity? "

"What's the main difference between density and viscosity? I would think that the more density something is the more viscosity it will have too.

I'm not quite seeing how the mass of a displaced fluid is equal to the force of buoyancy."

"I don't really understand the concept of buoyancy."

"Can you explain or give me a better example of Bernoulli's principles "