PHYS 1100 Quiz 3 (Copy)

How is a change in kinetic energy related to work?

A change in kinetic energy is a form of work.

What is meant by an isolated system?

A collection of objects that can interact with each other, but not with anything else

What did Carnot say a steam engine should more properly be called?

A heat engine

What is the smallest amount of a compound called?

A molecule

List some examples of conservative mechanical systems.

A pendulum, a ball rolling up and down the sides of a valley, orbit of planets

Approximately how many different kinds of atoms are there?

About 100 chemically different kinds

In which direction does heat flow?

Always from hot to cold

How is kinetic energy related to mass and velocity?

An object's kinetic energy was calculated by mass times the square of its velocity, and later a factor of one-half was included.

What are molecules made of?

Atoms

How is the kinetic energy of an object changed?

By accelerating the force acting on it, or changing the distance the object travels

How can the change in kinetic energy be determined from a force-distance graph?

By calculating the area under the force versus distance curve

How can the change in momentum be determined from a force-time graph?

By calculating the area underneath the force-time curve.

How is the momentum of an object changed?

By changing the force acting on it, or changing the time the force is allowed to act

In what two ways can you double the amount of work done?

By doubling the applied force or doubling the distance over which the force is applied.

How can you raise the temperature of the steam in a steam engine?

By producing the steam at a higher pressure

Explain specific heat and latent heat at the molecular level.

Depending on the geometric arrangements of the atoms in a molecule, different modes of motion are possible. Thus the specific heats of various compounds will be different because averaging will be different.

Christian Huygens

Dutch physicist who propoosed law of conservation of momentum as a law

In which type of collisions is kinetic energy conserved?

Elastic collisions

What is potential energy?

Energy associated with an object because of its position or configuration.

Thomas Newcomen

English blacksmith who constructed the first steam engine

Antoine Lavoisier

Furthered the idea that heat was a fluid

Who was the first scientist to recognize the theory of conservation of energy?

German physician, Julius Robert Mayer.

Hermann von Helmholtz

German physician, published "On the Conservation of Force" and arrived at conclusion of conservation of energy separate from Mayer

What are some forms of potential energy?

Gravitational, electrical, chemical, nuclear

Describe how Mayer arrived at his theory of conservation of energy.

He noticed that blood was redder in the tropics than in Germany; he heard the oxidation theory of blood and reasoned that because the body needs to produce

How did Joule determine the mechanical work equivalent of heat?

He set up a metal cylinder suspended by a rope over a pulley so he could measure the force of the cylinder and the distance it falls, in order to calculate the mechanical work exactly.

Name three problem phenomena to the caloric theory.

Heat is generated by friction, the expansion and contraction of gases, mechanical work can create heat.

Explain the difference between heat and temperature.

Heat refers to the amount, while temperature refers to the degree or concentration.

Lord Kelvin

Helped get Mayer's ideas accepted; recognized transfer of mechanical energy into heat energy

What is a conservation law?

If there is a conservation law for some quantity, then the total amount of that quantity is maintained at a constant value for all time in an isolated system.

When energy is lost in the above examples (conservative mechanical systems), where does it go?

It turns into heat

How does the caloric theory explain heat created by work?

It's not possible--creating heat by work would be creating more caloric fluid, which cannot be done.

Matthew Boulton

James Watt's partner

Name the three co-discovers of the idea of conservation of energy.

Julius Robert Mayer, James Joule, and Hermann von Helmholtz.

What was Lord Kelvin's contribution to the theory of conservation of energy?

Kelvin recognized the importance of Joule's work and helped it gain acceptance by the Royal Society of London. Kelvin noticed that heat and mechanical work must be two different forms of the same thing - energy.

List and define all of the possible forms of energy.

Kinetic: the energy associated with a body due to its motion. Heat: energy added to or taken from the microscopic modes of motion of the individual molecules of matter. Potential: energy associated with the shape, configuration, or position of an object in a force field. Radiant: electromagnetic radiation such as light. Mass:transformation of mass into energy in a a chemical reaction.

Count Rumford

Measured amt of heat generated by boring a cannon; famous experiment

Gay-Lussac

Measured the temperature of a gas allowed to expand in an evacuated chamber

What are two important consequences of Joule's work?

Mechanical work can produce heat, and the clue about how to construct a new theory of heat.

Are kinetic energy and momentum both vectors?

No. Momentum is a vector, but kinetic energy is a scalar quantity.

How much did the temperature rise in Joule's churn?

Not very much; the temperature rise was very small

How is the heat capacity of an object related to its specific heat?

Objects that have a high heat capacity will also have a high specific heat.

Define latent heat of vaporization.

Once water reaches its boiling point, you can keep turning up the heat on it but the water's temperature will not rise. This heat that is still going into the water is being turned into a hidden heat, which is the latent heat of vaporization.

James Watt

Patenter and creator of first efficient steam engine

Where are the kinetic and potential energies maximum and minimum in these conservative mechanical systems?

Potential energy's maximum is when the object is at its highest, and at its minimum when the object is lowest. Kinetic energy is the opposite.

Define pressure. How is it related to temperature?

Pressure is the average force exerted by molecules on the wall as they hit and rebound. As the temperature rises, so does the pressure because the molecules would have more kinetic energy.

What are atoms made of?

Protons, neutrons, and electrons.

Sadi Carnot

Published On the Motive Power of Fire, theoretical analysis of generation of heat by motion

Julius Robert Mayer

Ship surgeon, noticed Caribbean blood darker than German blood; conservation of energy

James Joule

Studied whether mechanical work could turn into heat; churn experiment

Define latent heat of melting.

The additional, hidden heat required to melt ice once it reaches its melting point

Define specific heat.

The amount of heat necessary to raise one gram of the material by one degree Celsius.

Define heat capacity.

The amount of heat needed to raise the temperature of an object one degree Celsius.

Define a calorie.

The amount of heat required to raise the temperature of one gram of water one degree celsius.

Briefly describe the caloric theory of heat.

The caloric theory of heat is the theory that heat was a fluid that flows from hot objects to colder ones.

Describe Joule's churn experiment.

The experiment consisted of a paddle wheel inside a cylinder of water, with vanes placed inside the cylinder that just barely allowed the paddles to pass and kept the water from swirling with the paddles. Joule wanted to see if the temperature of the water could be raised just by rotating the paddle.

What was a steam engine's real source of power?

The fuel being burned underneath the boiler.

How does temperature relate to the motion of molecules?

The higher the temperature, the faster and more freely the molecules are able to move. The lower the temperature, the less the molecules move.

What is Brownian movement?

The irregular movement of a very small particle suspended in a liquid solution.

What is the definition of work?

The product of force times distance.

What is a quark?

The smaller units that build up protons and neutrons.

How did Carnot compare a steam engine to a waterwheel?

The waterwheel derives its power from the flow of water from a higher elevation to a lower one. The larger the wheel, the more work could be done. Carnot suggested that because of this, a steam engine could do more work if the heat was made to flow over a larger temperature difference.

How many compounds are there?

There are hundreds of thousands of different chemical compounds

Why are conservation laws important in physics?

They allow us to increase our ability to predict exactly what will happen in increasingly complex situations.

What substance is used as the standard for specific heat?

Water

Describe what is happening on the molecular level for a gas, liquid and solid.

When molecules are a gas, they are not bound to each other and are free to move in any direction whatsoever and to spin and vibrate. In the liquid state, the molecules are still fairly free to move about and collide with each other as they move. There exists a small attraction between all the molecules in a liquid, and they add up to prevent a molecule from leaving the liquid. In a solid, the molecules are moving so slowly that the small forces on each one from the nearby molecules hold it in one place. They do not move among the other molecules, and it can only have vibrational motion.

Describe caloric fluid

a massless, colorless fluid that was conserved in its total amount in the universe. It was the fluid of heat.

What causes heat flow?

the difference in temperature between the two objects.