Thermodynamics

Fluids & Thermodynamics

Fluids: Density, Archimedes, Pressure, Buoyancy, Pascal, Bernoulli

Multiple Choice

Density is

• the weight of a fixed mass of something

• the volume of a fixed weight of something

• the weight of a fixed volume of something

• the ratio of mass to volume

Multiple Choice

Why does a hot air balloon float in air?

• Air is less dense than water.

• The density of hot air is less than the density of cold air.

• Air is denser on cold days.

• The overall density of the balloon and its basket is less than the density of the air.

Multiple Choice

Why would the amount of salt in water make an egg float or sink and why?

• Sink, salt makes the water heavier

• Float, the waters density is greater with salt added

• Sink, the egg is made from freshwater

• Float- adding salt makes the egg taste better so the water upvotes it

Multiple Choice

The density of fresh water is 1 g/cm³.

Imagine the clay boat you just designed has a density of 0.8 g/cm³. What would happen to your boat if you placed it in fresh water?

• sink, cannot make clay float

• float

• neutrally buoyant

• no way of knowing what would happen

Multiple Choice

If a 2.2mL object has a mass of 3.6 g and you put it into water (density =1.0g/mL,) will it sink or float?

• sink

• float

Multiple Choice

What do we call the the amount of force exerted on a certain area?

• density

• pressure

• weight

• pounds

Multiple Choice

The picture shows two completely identical mason jars. They're both filled with the same gas, only one of them has more in it (more molecules). What can you say about the pressures of both jars?

• P₁ > P₂ (greater pressure in jar 1)

• P₁< P₂ (greater pressure in jar 2)

• P₁ = P₂ (same pressure in both)

• There's not enough info to tell

Multiple Choice

For a given Force, When area increases...

• pressure increases

• pressure decreases

• pressure stays the same

• pressure increases then decreases

Multiple Choice

When pressure is applied to a confined fluid, the increase in pressure is transmitted equally to all parts of the fluid. This fact is called________.

• Pascal's Principle

• Newton's Principle

• Archimedes' Principle

• Bernoulli's Principle

Multiple Choice

Archimedes' Principle states that...

• The buoyant force acting on an object equals the volume of the fluid displaced by the object.

• The buoyant force acting on an object equals the weight (force of gravity) of the fluid displaced by the object.

• The buoyant force acting on an object will always be equal.

Multiple Choice

Water is about 1,000 times more ___ than air and therefore exerts greater pressure than air.

• dense

• heavy

• buoyant

• fluid

Multiple Choice

When the pressure is 16 kb, what is the depth in the earth's layers?

• 20km

• 53km

• 71km

• 90km

Multiple Choice

What is the SI unit use for hydraulic pressure?

• Kg/m³

• Pa

• Litre

• Kilometer

Multiple Choice

What does viscosity mean?

• How close the particles are together.

• The amount of matter in a substance.

• How easily a fluid flows.

• How dense a fluid is.

Multiple Choice

Pneumatics is the name for an enclosed, pressurized system filled with...

• water

• air

• oil

• helium

Multiple Choice

Car brakes and car jacks are examples of

• hydraulic systems
• archimedes' principle
• atmospheric pressure
• buoyancy

Multiple Choice

Fluids flow

• only when warmed up.

• from regions of low pressure to regions of high pressure.

• until evenly spread out.

• from high to low pressure.

Multiple Choice

The rule that states that a stream of fast-moving fluid exerts less pressure than the surrounding fluid.

• pascal's principle

• bernoulli's principle

• archimedes' principle

• Newton's Law

Multiple Choice

How does air pressure change as you go from the top of a mountain to sea level?

• pressure increases

• pressure decreases

• pressure stays the same

• it depends of the weather

Multiple Choice

This principle states that the faster a fluid moves, the less pressure the fluid exerts.

• Bernoulli's Principle

• Newton's Principle

• Pascal's Principle

• Archimedes' Principle

Multiple Choice

Where will air move faster - above or below an airplane wing?

• above

• below

Multiple Choice

Where will the pressure be greater - above or below the wing?

• above

• below

• mmm, wings

Multiple Choice

Which principle do airplanes take advantage of to fly?

• Archimedes' Principle

• Bernoulli's Principle

• Pascal's Principle

• The Vice Principal

Multiple Choice

Which lever configuration is most similar to the hydraulic system pictured?

Multiple Choice

What is the force up on the mailbox?

• 1210 N

• 8000 N

• 7744 N

• 5655 N

Thermodynamics: Temperature, Heat, Work, Entropy

Multiple Choice

What are the states of matter?

• solid, liquid, and gasoline

• ice, water, vapor

• earth, water, air, fire

• solid, liquid, and gas

• solid, liquid, gas, plasma

Multiple Choice

Temperature is a measure of the...

• total energy in a substance

• total kinetic energy in a substance

• average potential energy in a substance

• average kinetic energy of molecules in a substance

Multiple Choice

When thermal energy is added to a substance, the substance's particles move:

• More rapidly at an increased diestance from each other.
• More rapidly with less distance between each other.
• More slowly with a greater distance between each other.
• More slowly with a reduced distance between each other.

Multiple Choice

The term fluids generally applies to:

• solid and liquid

• liquid and gas

• solid and plasma

• water only

Multiple Choice

These statements are about the particle model of matter. Which one is not correct?

• Liquids are hard to compress because their particles are very close together

• Gases expand to fill their container because there are only weak forces between the particles

• Liquids can flow because there are only very weak forces between the particles

• Solids have a fixed shape because there are very strong forces between the particles

Multiple Choice

Which statements below is INCORRECT about liquids and gases?

• Liquids possess greater kinetic energy than gases.

• Gases have weak molecular force of attraction while liquids have a moderate force of attraction.

• Liquids have a definite size where gases can expand to fill any closed container.

• Gases are easily compressed where liquids are not.

Multiple Choice

Why do solids expand when they are heated?

• The particles get bigger

• The particles vibrate more and take up more space

• The particles vibrate more and get closer together

• The particles stick together

Multiple Choice

If the pressure inside a container of gas has decreased, it must have been caused by...

• adding heat to the gas or increasing the volume of the gas

• removing heat from the gas or decreasing the volume of the gas

• adding heat to the gas or decreasing the volume of the gas

• removing heat from the gas or increasing the volume of the gas

Multiple Choice

Water droplets condensing on the inside of a window on a cold day. Is this process exothermic or endothermic?

• Gases condense to form liquids. Gases are moving faster than liquids, the air around the window has a higher temperature/kinetic energy. Releasing energy to get water droplets, which is is Exothermic

• Gases condense to form liquids. Gases are moving faster than liquids, the air around the window has a higher temperature/kinetic energy. Releasing energy to get water droplets, which is is Endothermic

• Gases condense to form liquids. Gases particles are moving slower than liquids. Releasing energy to get water droplets, which is is Endothermic

• Gases condense to form liquids. Gases particles are moving slower than liquids. Releasing energy to get water droplets, which is is Exothermic

Multiple Choice

1200 J of heat are added to a sample of gas while the gas does 400 J of work on the environment. What is the change in internal energy of the gas? (think positive and negative)

• 800 J

• 1600 J

• -800 J

• -1600 J

Multiple Choice

Thermal energy always moves:

• From a high temperature object to a lower temperature object.
• From a lower temperature object to a higher temperature object.
• From an object with lower kinetic energy to an object with higher kinetic energy.
• From an object of higher mass to an object of lower mass.

Multiple Choice

A substance with a high specific heat:

• Is always extremely hot.
• Requires a lot of energy to become hot.
• Is not heavy.
• Does not requires a lot of energy to become hot.

Multiple Choice

You have a gas that has a pressure of 2 ATM and a volume of 10L.  What would be the new volume if the pressure was changed to 1 ATM?

• 5 L
• 20 L
• It would stay at 10L
• 1 L

Multiple Choice

Choose the correct equation to solve:

If the pressure exerted by a gas at 298 K in a volume of 0.044 L is 3.81 atm, how many moles of gas are present?

• P1/T1 = P2/T2

• PV = nRT

• V1/n1 = V2/n2

• P1V1 = P2V2

Multiple Choice

choose the correct equation-

A gas fills a balloon at a temperature of 27 ^oC and 1 atm of pressure. What will the pressure of the balloon be if the gas is heated to 127 ^oC?

• P1V1 = P2V2

• PV = nRT

• P1/T1 = P2/T2

• V1/T1 = V2/T2

Multiple Choice

Heat transfer by convection occurs when...

• electrons bump into other electrons
• large numbers of atoms move from place to place
• atoms give off heat in the form of electromagnetic waves
• electromagnetic waves travel from place to place through a vacuum

Multiple Choice

Heat transfer by conduction occurs when...

• particles bump into each other
• large numbers of atoms move from place to place
• atoms give off heat in the form of electromagnetic waves
• electromagnetic waves travel from place to place through a vacuum

Multiple Choice

Heat travels from the sun to the earth by the process of...

• conduction
• convection
• radiation
• insulation

Multiple Choice

The second  law of thermodynamics states that entropy of a system  tends to ______________. 

• increase
• decrease
• stay constant
• fluctuate wildly

Multiple Choice

Which statement is true about the ENTROPY?

• Entropy refers to DISORDER, the unusable energy that escapes a system.

• Entropy refers to the balance of temperature among two or more systems.

• Entropy refers to the average kinetic energy of the molecules.

• Entropy refers to the inability to destroy or create energy.

Multiple Choice

Which best describes ENTROPY?

• Useful heat energy needed to drive an engine

• Heat that can be stored to be used at a later date

• Random energy that escapes from the system

• A state of order in a physical system

Multiple Choice

Which law of thermodynamics states that absolute zero cannot be reached?

• 1st

• 2nd

• 3rd

• zeroth law