Science Chapter 8 - Review

Question 1

What is viscosity and how does temperature affect it?

Answer 1

Viscosity is the resistance to a fluid. The Viscosity of a fluid can changed depending on it’s temperature. If a fluid is heated, its viscosity lowers. The opposite is also true.

Question 2

Explain The change of Viscosities due to temperature using the particle theory of matter

Answer 2

Liquid particles move past each other and when heated, they move quicker as well as lose some of their overall attraction to each other. The attraction becoming less makes the fluids flow faster and there viscosity less as well

Question 3

How does temperature affect the viscosity of gasses? Explain this change using the particle theory of matter.

Answer 3

Temperature affects the viscosity of gasses in a different way than liquids. Gas particles are far apart and when they are heated they gain more attraction and begin to bump into each other. All this bumping causes friction between the particles and therefore, slows the gas down, and raises its viscosity.

Question 4

What is Density?

Answer 4

Density is the amount of mass contained in a given volume. Density describes how closely packed together particles are in a substance.

Question 5

How does temperature affects substances densities? Explain with the particle theory of matter.

Answer 5

All substances densities can change. If the substance is hot, its density is low. This also applies to the opposite. This can be explained using the particle theory of matter. When a substance is heated, they speed up and lose some of their attraction. This loss of attraction makes the spaces between particles bigger and their density low.

Question 6

How do we calculate density?

Answer 6

Density is the ratio of mass to volume. We Measure…
Liquids in g/ml
Gasses in kg/l
Solids in g/cm3
The formula for this is: Density = Mass / Volume

Question 7

What is Buoyancy and Buoyant force?

Answer 7

Buoyancy is the tendency of an object in a fluid to rise or sink due to density differences within its surroundings. We are able to float in a pool even when gravity pushes us down due to a force exerted by the water holding us up called the buoyant force.

Question 8

What are the three points you need to establish if an object will sink or float?

Answer 8

The three points are…
An object will RISE in a fluid when:
- The density of the object is less than the fluid’s density
- The buoyant force on the object is greater than the force of gravity on the object
An object will SINK in a fluid when
- The density of the object is greater than the fluid’s density
- The buoyant force on the object is less than the force of gravity on the object
An Object will FLOAT in a fluid when
The density of the object is equal to the fluid’s density
- The buoyant force on the object is equal to the force of gravity on the object

Question 9

What was Archimedes’ Principle?

Answer 9

Archimedes principle is used to find the weight of a substance. We put a rock in a bucket that’s full, some of the water spills out. The principle states that the water that fell out is the weight of the rock

Question 10

What are some examples of where the properties of buoyancy is used?

Answer 10

In the textbook, they give us two examples…
A sperm whale using its special organ that can fill and empty water to rise or descend in water
A hot air balloon using air and hot air to rise and fall in the sky

Question 11

What is a plimsoll line?

Answer 11

Near the bottom of a cargo ship, yo will see the plimsoll line. This line shows where the boat should be floating safely in a certain type of water.

Question 12

What is pressure?

Answer 12

Pressure is the amount of force applied to a given area.

Question 13

How do we calculate pressure?

Answer 13

We use a formula to calculate pressure…
Pressure - Force / Area

The unit for measuring pressure is pascals ( PA)
The unit for measuring force is newtons ( N )
The unit for measuring area is meters2 ( m2 )

Question 14

How does Air pressure change?

Answer 14

Air pressure becomes weaker the higher you get from the sea level. This also means its harder to breath. This factor is used in weather balloons as we return our weather balloons by making them rise so high, they pop

Question 15

What is the relationship between pressure and depth?

Answer 15

The further you get in a body of water, the higher the water pressure becomes. This is why if we make a hole at the bottom of a soda can, the pop will rush out faster than if we did this on the top of the can

Question 16

What is the relationship between pressure and fluid flow.

Answer 16

One of the most common rules of pressure is that an area of higher pressure will always go towards an area of lower pressure. This is why vacuums work an suck up dirt.

Question 17

What is the relationship between pressure and temperature?

Answer 17

When the temperature of a fluid increases, the pressure follows. If we heat up a soda can, the pressure inside it will be higher.

Question 18

What is compression? What fluids are compressible and incompressible?

Answer 18

Compression is a decrease in volume due to force. when we kick a soccer ball and our feet make a temporary dent in it, that is compression. Because gasses have big spaces inbetween there partices and liquids don’t, gasses are compressible while liquids are incompressible.