When do energy conversions occur

Now the energy changes in the engine can start. In the fuel tank the diesel fuel is stored chemical energy waiting to happen. Sometimes people call energy waiting to happen potential energy. Squirt diesel fuel into a diesel engine cylinder and suddenly the fuel is burning so fast and so hot we call it an explosion.

The potential chemical energy that was so quietly waiting in the diesel fuel is turned very quickly into heat. The heated air and combustion products in the cylinder expand, the piston is pushed down by the expanding air pressure, the crankshaft turns, and mechanical work is done. Chemical energy was transformed into mechanical work. Ta Da! On a locomotive the diesel engine crankshaft turns an alternator which converts mechanical energy into electrical energy. The electrical energy goes to giant traction motors which convert the electrical energy back into the rotating mechanical torque that turns the wheels.

The turning wheels push the locomotive forward. Now the mechanical energy becomes the kinetic energy of motion of the whole coal train. Don't get in front of it, because it will require a lot of brake friction turned into heat to stop this behemoth. As explained elsewhere, all of this energy eventually becomes low grade energy from friction and from heat rejected by the engine.

This raises the surrounding air temperature a little bit. Eventually the energy is radiated back out into space. If it didn't the earth would keep getting warmer and warmer, and we would all find things pretty uncomfortable. In one liter of diesel fuel there are approximately 39, KJ 37, Btu of potential chemical energy waiting to be turned into heat. If all this energy could be turned into work which it can't it would be enough energy to lift a kg weight meters 13, feet above the earth.

All of the fuel energy, even the part that's turned into useful work, eventually ends up heating the air, then radiating out into space. Isn't Energy the Ability to do Work? You will learn from text books and other sources that the definition of energy is " the ability to do work ".

That is the standard definition. But we think the definition we are using, " that certain something inside stuff with the ability to make things happen ", is more helpful as an introduction to the concept of energy. For anything to happen work has to be done on something.

Even in the case of heat flow, which in classical thermodynamics is not considered a work process, work is being done on molecules or atoms. At some level work is always being done when something happens.

So we really are saying the same thing. Put a cd in your portable player, put on the headphones and flip the switch. Chemical energy that was "waiting around", doing nothing much but "sitting" in the battery being potential , suddenly starts turning into electrical energy.

The new electrical energy, formerly known as chemical, zips through some wires to the electric motor that spins the disc. Now the energy that used to be electrical has become the mechanical energy of the spinning disc.

An electrical signal from sensors that "read" the spinning disc, travels through a wire to the little speakers in the headphones. In the headphones, the electrical energy that carried the signal, now becomes sound energy sound waves. Where the Voices Inside Your Head Come From Inside your head, sound energy in your ears is changed into electrical and chemical signals that travel to a part of your brain where those signals are turned into a sensation we call music.

Your brain sends electrical signals to muscles in your legs, arms, face, and other places. Inside the muscle cells chemical energy is stored in glucose molecules see Introduction to Photosynthesis. The signals from your brain tell your muscles to contract. The muscles convert the stored chemical energy into mechanical work, and you start to move.

The process in plant and animal cells that converts glucose into work and heat is called respiration. The energy in the glucose came from a plant or animal you ate. By now, you should know from where the plant got the energy. You use a bunch of face muscles to smile. You move arm and leg muscles in a coordinated manner some people move in a more coordinated manner than others. You strut and gyrate to the music. Some people call this dancing.

You're busy thinking how cool you are while billions of cells in your body are busy coverting chemical energy into work and heat. You start to sing off key and too loudly because of the headphones. Singing requires using the diaphram muscles below your stomach to force air through the larnyx in your neck. Once again chemical energy in the muscles is changed into mechanical energy and heat. Then the mechanical energy in the contracting muscles is changed into mechanical pressure and flow energy kinetic of the air being pushed out of your lungs.

Energy can never be created or destroyed — it can only change from one form to another. When the fuel is burnt, the hot gas rushes out of the rocket due to the great heat and pressure produced by the release of chemical energy in burning. Energy transformation is when energy changes from one type to another.

While energy can be transferred or transformed, the total energy always remains the same. In a Flash Diagram showing how different forms of energy can be converted to another form of energy. Energy Conversion: Transfer and Transform Energy transfer is the movement of energy from one location to another.

Burning Questions. What is energy transfer? What is energy transformation? This equation applies to all previous examples; in those situations OE was constant, and so it subtracted out and was not directly considered.

The fact that energy is conserved and has many forms makes it very important. You will find that energy is discussed in many contexts, because it is involved in all processes. It will also become apparent that many situations are best understood in terms of energy and that problems are often most easily conceptualized and solved by considering energy.

When does OE play a role? One example occurs when a person eats. Food is oxidized with the release of carbon dioxide, water, and energy.

Some of this chemical energy is converted to kinetic energy when the person moves, to potential energy when the person changes altitude, and to thermal energy another form of OE. What are some other forms of energy?

You can probably name a number of forms of energy not yet discussed. Many of these will be covered in later chapters, but let us detail a few here. Electrical energy is a common form that is converted to many other forms and does work in a wide range of practical situations.

Fuels, such as gasoline and food, carry chemical energy that can be transferred to a system through oxidation. Chemical fuel can also produce electrical energy, such as in batteries. Batteries can in turn produce light, which is a very pure form of energy.

Most energy sources on Earth are in fact stored energy from the energy we receive from the Sun. We sometimes refer to this as radiant energy , or electromagnetic radiation, which includes visible light, infrared, and ultraviolet radiation.

Nuclear energy comes from processes that convert measurable amounts of mass into energy. Nuclear energy is transformed into the energy of sunlight, into electrical energy in power plants, and into the energy of the heat transfer and blast in weapons. Atoms and molecules inside all objects are in random motion. This internal mechanical energy from the random motions is called thermal energy , because it is related to the temperature of the object.

These and all other forms of energy can be converted into one another and can do work. Table 1 gives the amount of energy stored, used, or released from various objects and in various phenomena.

The range of energies and the variety of types and situations is impressive. You will find the following problem-solving strategies useful whenever you deal with energy. Click to run an interactive simulation to explore transformations between types of energy.

Specifically, this simulation deals with conversions between forms of mechanical, electrical, chemical, and light energy. Fossil Fuels. Nuclear Fuels. Acid Rain. Climate Change. Climate Feedback. Ocean Acidification.