Science - Fluids - 8.1 Viscosity and the Effects of Temperature Flashcards
The thickness or thinness of a fluid is a property called____
Viscosity
What is viscosity?
Viscosity is the resistance of a fluid to flow.
Fluids with ___ viscosity do not flow as easily as fluids with a __ viscosity.
Fluids with high viscosity do not flow as easily as fluids with a low viscosity.
What is one factor that can have a big effect on viscosity?
Temperature.
What happens as the temperature of a liquid increases? What happens as a result. (regarding the flow)
As the temperature of a liquid increases, its viscosity decreases. As a result, the fluid flows more easily. The warmer the liquid the faster it flows.
What happens as the temperature of a liquid decreases? What happens as a result. (regarding the flow)
As the temperature of a liquid decreases, the particles slow down. The result is that the viscosity increases. The cooler the liquid, the slower it flows.
What happens when heat is added to gas? What happens when the temperature decreases?
When heat is added to the gas, the particles move faster and collide more often, resulting in greeted resistance, or friction.
When the temperature decreases there is less friction and it flows faster.
What is Friction? The greater the friction between particles in any fluid, the lower or higher the viscosity?
Friction is a force that works to slow down motion as a result of surfaces rubbing against each other. The greater the friction between particles in any fluid, the higher the viscosity. A fluid with a high viscosity has a large amount of internal friction.
What happens as the temperature pf a gas increases. The warmer the gas the ____ it flows
As the temperature of a gas increases, friction increases, and so the viscosity of the gas increases. The warmer the gas the slower it flows.
What happens as the temperature of a gas decreases? (to the particles) What happens as a result?
As the temperature of a gas decreases, the particles slow down and collide less often, so there is less friction. As a result the viscosity decreases. The cooler the gas the faster it flows.
Do different substances have different viscosities? If so why?
Different substances have different viscosities because they are made of different particles with different forces of attraction between them.
What is one way to compare the viscosity of different fluids?
One way to compare the viscosity of different fluids is to compare their flow rates.
What is the flow rate of a fluid a measure of? What is flow rate determined? The greater the viscosity the ___ lower the flow rate. (lower or higher)
The flow rate of a fluid is a measure of the speed at which a fluid flows past a given point in a given time. Flow rate is determined by measuring the amount of fluid that flows past a given point in a given time. The greater the viscosity, the lower the flow rate.
What is density? And what does it describe?
Density is the amount of mass contained in a given volume. Density describes how closely packed together the particles are in a substance.
When is a substance is most dense and least dense? Why is it denser?
A substance is most dense when it is a solid and least when it is a gas. A solid is denser than a gas because the particles in solid are much closer together.
Why does a substance float but sink in others? (3 points)
- If the density of a substance is greater than the density of the fluid, the substance will sink.
- If the density of a substance is less than the density of the fluid, the substance will float.
- If the density of a substance is the same as the density of a fluid, the substance will “hover” in place.
How can metal boats float on water?
Because the boat consists of more than just metal. If you consider the density of the air inside the boat and the density of all the objects in the boat, you would find that the combined density of all parts of the boat is less than the density of the water. (shorter version: The average density of the boat is less than the average density of the water, so it will float.)
When will a submarine float and sink. Why?
A submarine will float when the tanks are filled with air and sink when the tanks are filled with water. (because of the combined/average density).
A substance can have different densities, depending on its temperature. Give an example.
For example the water on the surface of a lake floats on the cold water because it’s warmer, causing it to have a lower density than that cold water.
As the temperature of a substance increases, the particles move faster and farther apart. But, the volume increases even though the number of particles stays the same. With the same number of particles in a larger volume, what happens to the density.
The density decreases.
A substance generally has a greater density in its solid state than in its liquid and gas state. What is one exception.
One exception to this is water because the particles in water move slightly farther apart as the water freezes, so ice is less dense than liquid water.
What is density?
Density is the ratio of mass to volume.
What is the unit for measuring the density of liquids? Gases? Solids?
Liquids: grams per milliliter (g/mL).
Gases: kilograms per litre (kg/L).
Solids: grams per cubic centimetre (g/cm*3).
How do you calculate the density of a substance?
by dividing its mass by its volume.
On a density graph, a substance with a greater slope has ___ density tan a substance with a shallower slope.
A substance with a greater slope on the graph has a greater density than a substance with a shallower slope.
Wood floats on water or oil because pine wood is less dense
than some liquids.
Name fluids that are less dense than water/
Fluids that are less dense than water: Vegetable oil, rubbing alcohol, and gasoline.
Does wood float on water? If so, why?
Wood floats on water or oil because pine wood is less dense than some liquids.
What is a force? Give an example.
A force is a push or pull that acts on an object. For example, weight is the amount of downward pull on an object due to the force of gravity.
What is the measuring unit of force? What is one ___ approximately equal to?
Newton (N). One newton is approximately equal to the force you would exert to hold up a baseball.
What is buoyancy.
Buoyancy is the tendency of an object in a fluid to rise or sink due to density differences with its surroundings.
Earths ___ force attracts matter downward towards __. A fluid exerts an opposite force that pushes matter ___. The upward force exerted by a fluid is called the ____.
Earth’s gravitational force attracts matter downward toward Earth’s center. A fluid, however, exerts an opposite force that pushes matter upward. The upward force exerted by a fluid is called the buoyant force.
When will an object rise? (2 points)
- the density of the object is less than the density of the fluid
- the buoyant force on the object is greater than the force of gravity on the object
When will an object sink in a fluid? (2 points)
- the density of the object is greater than the density of the fluid
- the buoyant force on the object is less than the force of gravity on the object
When will an object float in a fluid? (2 points)
- the density of the object is equal to the density of the fluid
- the buoyant force on the object is equal to the force of gravity on the object.
Who is Archimedes? What does Archimedes’ principle state? Give an example (tin foil)
Archimedes is a Greek mathematician and inventor who discovered an important principle about buoyancy.
Archimedes’ principle states that the buoyant force on an object is equal to the weight of the fluid displaced by the object. (ex. Tin foil ball and boat. The boat takes up a much greater volume and displaces more fluid; therefore the buoyant force acting on the boat and its cargo is greater, so it floats.
Buoyancy is also an important factor in natural fluid systems. Give an example.
by changing the temperature of a sperm wales oil, it can dive deep or rise to the surface for air. (from its oil-filled organ solidifying and increasing its temperature or warming the oil to increase its density.)
List examples of transportation technologies that use the concept of buoyancy in their design. (4)
Ships can travel around the world thanks to ___
Hot air balloons, airships, and research platforms.
the buoyant force of water.
Why do ships sink lower in the water. What happens in the tropical and northern waters?
Ships sink lower in the water because freshwater is less dense than salt water. Warm water is less dense than cold water so the ship sinks lower in the water (tropical - northern waters)
The density variations in the world’s oceans and rivers are the reason why cargo ships have a __ on their __. What does the Plimsoll line show?What do the marks on the left and right indicate.
The Plimsoll line shows how heavily a ship can be safely loaded in different water conditions. The marks on the left indicate where the waterline should be in freshwater. The mark on the right indicates where the waterline should be in salt water.
