9.1 Fluids under pressure

How does pressure in fluids change with depth?

There is very little water pushing down on the water at the top of the tube.

#Lots more water pushing down at the bottom.=pressure at the bottom is higher.





water, air, and other fluids, pressure increases with depth.



The pressure of airat sea levelis called one atmosphere(1 atm).

=101.3Kpa



#with each 10m go deeper in the waterthan sea level, pressure goes up by 1 atm.(1 atm =10000kgpushing down on the area of 1 square meter)







Buoyancy

Buoyancy is the tendency for objects to rise or float in a fluid.

Buoyancy occurs because of differences in densityof the object and the fluid.



Buoyant force: Objects rise or float in a fluid because the fluid pushes up on them with a force.







Convection

The buoyant force us what makes heated air rises.

#The density of the heated air is less then the desity of the cooler air.

so the heated air rises, the cooler air sinks.

This transfer of heat throught the flow of a heated fluid is called convection.





#When the buoyant and the force of gravity are unbalanced, object will move direction to the larger force.

#When the two forces are balanced, no motion will occur.






examples:

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Questions of 8.3

Questions

1.A(n) _____is any substance that flows.

2.Explain what is viscosity?

3.what happened when the viscosity of a fluid decrease.

4.How can you compare the viscosity of different fluids?

5.What happens when a gas is heated?

6.The slower the fluid flow, the _____ the viscosity.

7.Heating a liguid ____ its viscosity.

8.Give some example of viscous liquid.

9. What does surface tension means?

10.The ____ of a liquid is the speed at which a fluid flows from one point to another.












Answers

1.fluid

2.The thinness or thickness of a liquid is a property of fluids calles viscosity.

3.When the viscosity of a fluid decrease, its flow rate increase.

4.You can compare the viscosity of different fluids by comparing their flow rate.

5.Heating a gas increase its viscosity.

6.higher.

7.Heating a liquid decreased its viscosity.

8.molasses, oil, honey.

9.The water particles at the surface attract each other in a way that makes the surface act like a skin.

10. flow rate

Questions of 8.2

Questions

1.Why can you compress a gas but not a liquid or a solid.

2.What does deformation means?

3.What is the formula of measures pressure.

4.____ is the amount of force that acts on a given area of an objects.

5. 1kPa=( )pa

6.What is the unit for pressure?

7.what is the symbol of pascal?

8.What is a compression.

9.Area is often measured in ____.

10.What will happened to the pressure if the force is decreased?
















Answers


1. There are a large amount of space between its particles.

2. Deformation means a change of shape without being force into a smaller volume.

3. p(pressure)=F(force)/A(area)

4. pressure

5. 1000Pa

6. kilopascal(kPa)

7.pa

8. Compression is a decrease in the volume of matter cause by a force.

9. square metres

10. The pressure will also decrease.

Chapter 8 questions

Questions

1.what is a difference between a contact force and an action-at-a-distance force?

2.How is weight different from mass?

3.A(n)______ is a push or a pull that acts on an object.

4.Force is measured in units called _____.

5.what is a balanced force.

6.What is an unbalanced force.

7. Give an example of a static electricity.

8.Give the examples of the types of forces.

9.What is the unit for weight?

10.What is the unit for mass?














Answers
1.contact force have effect only an objects that they touch.
Action-at-a-distance force acts on objects withput touching them.

2.Weight is the amount of force that gravity exerts on the mass of an object.
The mass of an object measured the amount of matter in it.

3.force

4. newtons

5.They are equal in size, and they act in opposite direction.

6.They are not equal in size, it acts in the direction of the stronger force.

7.lightening

8.Friction, tension, elastic, gravitation, magnetic, static electicity.

9.newtons

10.kilograms

8.3 Viscosity, Adhesion, and Cohesion

What is viscosity?



some fluids are thicker or thinner than others.
ex: water is thinner than honey.
ex:Molasses is thicker than vegetable oil.


The thinness or thickness of a liquids a property of fluids called vicosity.


Viscosity describes a fluid's resistance to flow.
A thick liquid has a greater viscosity than a thin liquid.
The thicker liquid is more resistant to flow.



How do heating and cooling affect viscosity?


To compare the vicosity of fluids, you can measure their fow rate.

Flow rate: The speed at which a fluid flow from one point to another.
ex: honey is more viscous than water, the flow rate of honey is slower than water.

If honey is heated, the particles that make up honey move farther apart.
Now the honey is more viscous than it was before.

If gas is heated, the particles that make up the gas move faster.
Heating a gas increase its viscousity.

• When the viscosity of a fluid decreases, its flow rate increase.
• You can compare the viscosity of different fluids by comparing their flow rate.
• Flow rate is also affected by adhesion and cohesion.
• The slower the fluid flows, the greater the viscosity.

What is cohesion?

The property fluids that makes the particles hold together because they are attracted to each other is called cohesion.

ex: The water drop takes the shape of a disc.

The water particles at the surface attract each other in a way that makes the surface act like a skin. This effect is called surface tension.

What is adhesion?

Adhesion is the attraction between particles of a fluid and another substances so that the fluid clings to it.

8.2 Pressure

What is pressure?

pressure is the amount of force that acts on on a given area of an object.
ex: which has more pressure?
a)dull pencil b)sharp pencil


How does pressure affect matter?

Pressure can cause a gas to be compressed.
ex: if you squeeze or press down a balloon, the shape of he balloon changed.

#The increased pressure on the balloon pushes the air particles closer together.

Compression is a decrease in the volume of matter cause by force.
When pressure is applied to matter , compression can result.

Deformation means a change of shape without being forced into a smaller volume.


what happeneds when a gas-filled container explodes?

The particles of a gas move faster and farther apart when energy is added? ans: it expands

The heated gas exerts more pressure on the inside of the container .
this added pressure can lead to an explosion.


How is pressure measured?

pressure=force/area
units for force and area:

force is measured in newtons(N).
area is often measured in square metres.
pressure is measured in units of newtonsper square metres.

A pressure that is equal to 1N/m2 is called a pascal.
pascal=Pa . This is a very small amount of pressure.

Pressure is often measured using a unit equal to 1000 Pa.
1ooo Pa=1 kilopascal(kPa)