Science

We wouldn't have a source of solar energy, wind energy, or hydroelectric energy anymore.

Imagine that the sun ran out of energy. What would happen to our energy resources on Earth?

Most of the energy will be converted to heat, as when the ball bounces it gets its shape manipulated and then it regains its shape - this would be the main factor. Another form of energy it would be converted into would be sound energy, because the ball makes a sound when it hits the ground. My friend's statement would not be correct as the energy has not disappeared, but is converted into different forms.

Imagine that you drop a ball. It bounces a few times and then it stops. Your friend says that the energy that the ball had is gone. Where did the energy go? Evaluate your friend's statement based on energy conservation.

One car may use more aerodynamics than the other. Also, that car can also have less moving parts, decreasing the friction and amount of energy lost.

Imagine two cars, one of which is more efficient than the other. Suggest two possible reasons one car is more efficient.

B. transferred from areas of lower temperatures to areas of higher temperatures

In an air conditioner, thermal energy is

Nuclear Energy

Name an energy resource that does NOT depend on the sun.

Thermal Energy - It depends partly on kinetic energy of the particles making up an object. Chemical Energy - It is a kind of potential energy because it depends on the arrangement of atoms in a molecule (energy of position).

Name two forms of energy, and relate them to kinetic or potential energy.

Renewable are resources that are replaced naturally or regenerate more quickly than they are used, while nonrenewable resources are resources that are unreplaceable or replaced less quickly than they are used up.

Renewable Resources and Nonrenewable Resources

No, it depends on the temperature of each bowl of soup. If one bowl has a higher temperature than the other, it will have more thermal energy than the other.

Someone claims that a large bowl of soup has more thermal energy than a small bowl of soup. Is this always true? Explain.

States of matter are the physical states that include, liquid, gas, and solid. A change of state is a physical change from one state of matter to the next.

States of Matter and Change of State

435. 136 J

Suppose 1.3 kg of water is heated from 20 C to 100 C. How much energy was transferred to the water? (Water's specific heat is 4,184 J/kg x C)

Temperature is the measure of average kinetic energy of the particles in matter. Thermal energy is the total kinetic energy of the particles of a substance.

Temperature and Thermal Energy

Heating the lid causes thermal expansion, which will make the lid bigger and easier to get off.

The metal lid is stuck on a glass jar of jelly. Explain why running hot water over the lid will help you get the lid off.

19. 2 J [heat = specific heat x mass x change in temperature]

The specific heat of lead si 128 J/kg x C. How much heat is needed to raise the temperature of a .015 kg sample of lead by 10 C?

B. Calories

The units of energy that you read on a food label are

Kinetic Energy

What happens to that energy after the skier races down the slope of the mountain?

Each metal has a different thermal expansion rate.

What is different about the two kinds of metal on the bimetallic strip of a thermostat coil?

Freezing

What is happening at the point where the line is horizontal?

Weight and Height

What two factors determine gravitational potential energy?

C. Thermal Energy

When energy changes from one form to another, some of the energy always changes into

When you hit a nail, your kinetic energy is transferred to the nail. Some of this kinetic energy will turn into thermal energy as it hits the nail, making the nailhead warm

When you hit a nail into a board by using a hammer, the head of the nail gets warm. In terms of kinetic and thermal energy, describe why you think the nail head gets warm.

D. Food is digested and used to regulate body temperature, charcoal is burned in a barbecue pit, and coal is burned to produce steam

Which of the following sentences describes a conversion from chemical energy to thermal energy?

C. 100 K

Which of the following temperatures is the lowest?

B. Nuclear Energy

Which of the following types of energy is not a renewable resource?

Potential Energy

Which part of mechanical energy does the girl in the picture below have the most of?

The soup could overflow its pot as it cooks because of thermal expansion. The soup will expand in volume as its temperature increases. If the soup is too close to the top of the pot, it will likely overflow as it expands.

Why do you think heating a full pot of soup on the stove could cause the soup to overflow?

No, a refrigerator takes the thermal energy from inside the fridge and distributes it to the outside of the fridge. If you were to add more thermal energy by opening the refrigerator door, the refrigerator will double the amount of heat energy being taken out. This would actually make the room warmer.

Would opening the refrigerator cool a room in a house? Explain your answer.

Nonrenewable resources

________ are used up more quickly than they are being replaced.

[Thermal Energy = Energy Given - Work Done] 80 - 60 = 20 J

A bike is pedaled with 80 J of energy and then coasts. It does 60 J of work in moving forward until it stops. How much of the energy that was put into the bike became thermal energy?

No, the sound energy does not contribute to stopping the car. Sound energy is just the particles of the air bumping into each other, so it does not slow the car.

A car that brakes suddenly come to a screeching halt. Is the sound energy produced in this conversion a useful form of energy? Explain your answer.

Thermal energy radiates from the campfire, reaching us and transferring to us.

Can you explain why you feel warm when you are standing near a campfire?

273 K

Convert 0 C to kelvins.

To test aerodynamics' effects, measure the efficiency of a slower car with more aerodynamics to the efficiency of a slower car with less aerodynamics.

Describe how you would test the two hypotheses you proposed in the question about two cars' efficiency. How would you determine whether one, both or neither hypothesis is a factor in the car's efficiency?

Not all of the cars' potential energy is converted into kinetic energy as the cars go down the first hill. Not all of the cars' kinetic energy is converted into potential energy as the cars go up the second hill. Some of it is changed into thermal energy because of friction.

Describe the energy conversions that take place on a roller coaster, and explain how energy is conserved.

The potential energy of a basketball is at its highest when the ball is at its greatest height. Then, it becomes converted to kinetic energy as the ball falls to the ground, and the kinetic energy is at its highest when the ball reaches the ground. When the ball bounces back up again, its kinetic energy converts back into potential energy and so on.

Describe the kinetic-potential energy conversions that occur when a basketball bounces.

A hydroelectric dam and a wind turbine both harness renewable sources of energy. Neither cause air pollution, but a hydroelectric dam can disrupt river life, whereas a wind turbine has hardly any effect on the environment.

Describe the similarities and differences between transforming energy in a hydroelectric dam and a wind turbine.

The compression of the air balloon is potential energy, and when it is released it is kinetic energy.

Describe what happens in terms of energy when you blow up a balloon and release it.

It depends on the position and arrangement of atoms in a compound.

Describe why chemical energy is a form of potential energy.

These energy exchanges are not changes in kinetic energy. They are changes in bonding energy between the molecules.

During a change of state, why doesn't the temperature of the substance change?

In a change of state, heat changes the arrangement of particles without changing their temperature.

Explain how heat affects matter during a change of state.

Thermal conductor is a material through which heat can transfer easily, while thermal insulator is a material through which heat is passed with difficulty (in less amount).

For each pair of terms, explain how the meanings of the terms differ: thermal conductor and thermal insulator

The exchange of thermal energy involved in evaporation and condensation is what makes a refrigerator work.

How are changes of state important in how a refrigerator works?

Energy is the capacity to do work

How are energy and work related?

They are formed from decayed organic matter of plants and animals that are millions of years old.

How are fossil fuels formed?

Temperature is a measure of the average kinetic energy or a substance.

How does temperature relate to kinetic energy?

400/100 = 4 m

A box has 400 J of gravitational potential energy, if the box weighs 100 N, how far above the ground is it?

Thermal expansion causes the air in the balloon to expand, making the balloon less dense. This decrease in density causes a buoyant force to be on the balloon and make it float.

In a hot-air balloon, air is heated by a flame. Explain how this enables the balloon to float in the air.

Renewable resources

There is a practically limitless supply of _________.

D. Velocity and Mass

Kinetic energy depends on

B. Less thermal energy and a higher temperature

Compared with the Pacific Ocean, a cup of hot chocolate has

Light energy to chemical energy

In plants, energy is transformed from

Both fossil fuels and biomass come from organic matter, are burned to generate energy, and cause air pollution when used. Biomass is renewable, but fossil fuels are not.

Compare fossil fuels and biomass as energy resources.

Solar heating systems are energy efficient, but the amount of heating they can accomplish could not be much use in cold climates. Overall, it seems they could be put to good use in a lot of places in the world and could save a lot of energy.

Compare the advantages and disadvantages of solar heating systems. What do you think their overall benefits are, compared with those of other heating systems?

Conduction is the transfer of thermal energy between objects that are touching. Heat is the transfer of thermal energy between objects that are different temperatures.

Conduction and Heat

A conductor is a substance that transfers energy rapidly by conduction. An insulator is a substance that does not conduct thermal energy well.

Conductor and Insulator

Convection is the transfer of thermal energy by the circulation or movement of a liquid or gas. Radiation is the transfer of energy as electromagnetic waves.

Convection and Radiation

B. Weight and Height

Gravitational potential energy depends on

The down jacket has a layer of insulation, preventing thermal energy from your body from escaping into the air. Since this thermal energy is not lost to the air, we are able to stay "warm."

How does a down jacket keep you warm?

Radiation transfers thermal energy through space without a medium, but conduction and convection require a medium.

How is radiation different from both conduction and convection?

28.9 degrees C; 302.039 K

The weather forecast calls for a temperature of 84 F. What is the corresponding temperature in degrees Celsius? In Kelvins?

Conduction is the direct transfer of thermal energy between moving objects, convection is the transfer of thermal energy by convection currents through a fluid that results when different areas are different temperatures, and radiation is the transfer of thermal energy through space by electromagnetic waves.

What are the differences between conduction, convection and radiation?

0 degrees Celsius

What is the freezing point of this liquid?

The graph shows the change of a state of matter. (liquid is solidifying)

What physical change does this graph illustrate?

150,000 calories

When burned in a calorimeter, a sample of popcorn released 627,600 J. How much energy, in Calories, did the popcorn have?

Thermal energy was transferred from the table to the glass of cold water.

A glass of cold water whose particles had a low average kinetic energy was placed on a table. The average kinetic energy in the cold water increased, while the kinetic energy if the part of the table under the glass decreased. What do you think happened?

As the potential energy you have at the top of the hill turns into kinetic energy as you go down, some kinetic energy is turned into thermal energy from friction. Perpetual motion is impossible because energy conversions always result in energy being lost as heat.

After you coast down a hill on your bike, you will eventually come to a complete stop. Use this fact to explain why perpetual motion is impossible.

In a hot water heating system, hot water is circulated into rooms, where it heats the air. In the warm air heating system, air is heated by a central furnace and then circulated into the room.

Compare a hot-water heating system with a warm-air heating system.

-173 C

Convert 100 K to degrees Celsius.

1.1 C

Convert 34 F to degrees Celsius.

95 F

Convert 35 C to degrees Fahrenheit.

A Hair Dryer: electrical energy enters the hair dryer, then is converted into kinetic energy through the fan. The fan then uses kinetic energy to blow air through hot wires, changing the kinetic energy to thermal energy before it blows that air out of the dryer.

Describe a case in which electrical energy is converted into thermal energy.

When the temperature of an object is raised, its particles move around more, so they take more space. This causes the entire object to expand.

Describe the process of thermal expansion.

No; temperature is the average kinetic energy of particles of a substance. If the individual particles of two objects have the same average kinetic energy, they are at the same temperature regardless of how much matter is in each object.

Does temperature depend on the amount of the substance? Explain.

Thermal expansion causes the density of a substance to decrease, because the same mass takes up more volume.

During thermal expansion, what happens to the density of a substance?

Energy resources are natural sources of energy that can be converted into other forms of energy while fossil fuels are energy resources that come from decayed matter from plants and animals that lived millions of years ago.

Energy Resources and Fossil Fuels

Within a closed system, objects transfer energy to each other. Energy is conserved because energy is not created nor destroyed, it only changes form.

Explain what a closed system is, and how energy is conserved within it.

A high-speed collision may cause more damage to vehicles than a low-speed collision. Since speed is a key factor in kinetic energy, there is more kinetic energy in a high-speed collision. When a collision happens, the high-speed collision will demand more energy and force considering it harbors more, therefore exerting more force when it hits, making the crash much more dangerous. The higher the energy and force, the more damage there will be.

Explain why a high-speed collision may cause more damage to vehicles than a low-speed collision.

Friction is a force that opposes motion between two surfaces, while the law of conservation of energy is a law that states energy is never created or lost, it simply changes form.

Friction and the Law of Conservation of Energy

When a person jumps off a diving board, the potential energy of their position is changed into kinetic energy of them diving from the board. When light energy from the sun is converted to chemical energy through photosynthesis. When a hair dryer is turned on, electrical energy is changed into kinetic energy of the turning fan and thermal energy of the hot coils inside the hair dryer.

Give three examples of one form of energy being converted into another form.

A heat engine is an engine that uses thermal energy to do work. Thermal pollution is the raising of the temperature of an environment from thermal waste.

Heat Engine and Thermal Pollution

You ingest food (vegetables, fruits, etc.) that have taken on energy throughout its life. Plants have gone through a chemical change (photosynthesis) that has given it chemical energy. So, when you ingest fruits and vegetables, you too take in that chemical energy.

How does your body get the energy that it needs?

No, efficiency depends on the ratio of energy input to energy output, and you do not know the energy input. If the energy input is much higher than the energy output, the car is not efficient.

If someone says that a car has high energy output, can you conclude that the car is efficient? Explain.

A change from one form of energy to another

In your own words, write a definition for the term energy conversion.

The capacity to do work

In your own words, write a definition for the term energy.

A nonrenewable energy resource formed from the remains of organisms that lived long ago.

In your own words, write a definition for the term fossil fuel.

A measure of how hot (or cold) something is; specifically, a measure of the average kinetic energy of the particles in an object

In your own words, write a definition for the term temperature.

Most of the energy is used during the months of January, February, March and December. (mainly winter months)

Look at the graph below. It shows the cost of heating a certain house month by month over the course of a year. During which times of the year is the most energy used for heating? Explain your answer.

The potential energy from the position of the pole will have to quickly transfer to kinetic energy to push the pole vaulter over the barrier.

Look at the photo below. Beginning with the pole vaulter's breakfast, trace the energy conversions necessary for the event shown to take place.

A - Conduction B - Convection C - Radiation

Look at the photo below. It shows examples of heat transfer by conduction, convection, and radiation, Indicate which type of heat transfer is happening next to each letter.

In this case, heat comes from a chemical reaction that absorbs thermal energy.

Many cold packs used for sports injuries are activated by bending the package, causing the substances inside to chemically react. How is heat involved in this process?

Mechanical energy is the total kinetic and potential energy of an object while energy conversion is the change of energy from one form to the other.

Mechanical Energy and Energy Conversion

D. Machines have friction

Perpetual motion is impossible because

Potential energy is the energy of the position of an object, while kinetic energy is the energy of the motion of an object.

Potential Energy and Kinetic Energy

Electrical energy comes from power generators, which may be run by burning fossil fuels, which carry stored energy from the sun harnessed in plants and animals.

Trace electrical energy back to the sun.

When two objects at different temperatures are in contact, the thermal energy passes from the warmer object to the cooler object.

Two objects at different temperatures are in contact. Which of the following happens to their thermal energy?

They do not stay at the same temperature because bigger objects needs larger amount of thermal energy.

Two objects have the same total thermal energy. They are different sizes. Are they at the same temperature? Explain.

The same insulation is used for the floors and FIG. Heat engine converts heat energy to mechanical energy. Thermal pollution is temperature increase in a body of water that is caused by human activity and that has a harmful effect on water quality and on the ability of that body of water to support life.

Use each of the following terms in a separate sentence: insulation, heat engine, and thermal pollution.

Among the four known states of matter, plasma is the least found on the Earth's crust. When ice melts, a change of state takes place.

Use each of the following terms in a separate sentence: states of matter and change of state.

Thermal expansion causes mercury in a thermometer to change volume, allowing it to measure temperature. Absolute zero is the temperature at which there is no thermal energy at all.

Use each of the following terms in a separate sentence: thermal expansion and absolute zero.

Change of one kind of energy into another is called energy conversion. As an object falls, its potential energy changes into kinetic energy.

Use the following terms in the same sentence: friction and the law of conservation of energy.

Kinetic energy is the energy of an object's motion, potential energy is the energy of an object's position, and mechanical energy is the amount of work an object can do because its kinetic and potential energies.

Use the following terms in the same sentence: kinetic energy, potential energy, and mechanical energy.

The U.S. is obtaining most of its energy from nonrenewable resources, which could be causing nonrenewable resources to run out. So, renewable resources should be used more to conserve those nonrenewable resources.

Use the pi chart below to explain why renewable resources are becoming more important to the U.S.

The speed of its particles and the attraction between them determines a substance's state.

What determines a substance's state?

A. The motion of its particles

What determines an object's thermal energy?

Heat is the transfer of thermal energy between objects at different temperature

What is heat?

Machines can help you use energy by converting it into the form that you need.

What is the role of machines in energy conversions?

500 x 100 = 5000 J

What is the skier's gravitational potential energy at point A?

500 x 5 = 2500 J

What is the skier's gravitational potential energy at point B?

Potential Energy

What kind of energy does the skier have at the top of the slope?

When water evaporates, it absorbs thermal energy. This thermal energy comes from the air around it, so the air must lose thermal energy for the water to gain thermal energy. Therefore, the air cools.

When water evaporates (changes from a liquid to a gas), the air near the water's surface becomes cooler. Explain why.

D. Work is done to transfer thermal energy from cooler areas to warmer areas

Which of the following describes how cooling systems transfer thermal energy?

A. Wind

Which of the following is a renewable resource?

A. 0 K

Which of the following is the coldest temperature possible?

C. Metal (good conductor not insulator)

Which of the following materials would NOT be a good insulator?

Many metal cooking utensils have wooden handles because wood is a poor conductor of heat, so you can hold the wooden handle of a hot pot, for instance, without being burned.

Why do many metal cooking utensils have wooden handles?