For example, engines, such as those in cars or trains, do work by converting thermal energy into mechanical energy. Also, refrigerators remove thermal energy from a cool region into a warm region.
On a larger scale, recent scientific research has been aiming to convert solar energy to thermal energy in order to create head and electricity. For example,scientific research centers such as NASA explore the uses and applications of thermal energy in order to provide for more efficient energy production. This power system would convert solar energy into thermal energy which would then be used to produce electrical power and heat.
However, converting solar energy to thermal energy has been found to be much easier and much more feasible when systems are not in a state of thermodynamic equilibrium. Rather, scientists have proposed, a moving object or a running fluid can allow the energy to be converted into thermal energy.
Thus the flow of thermal energy is constantly increasing entropy. Thermal Energy and Temperature Thermal energy is directly proportional to the temperature within a given system recall that a system is the subject of interest while the surroundings are located outside of the systems and the two interact via energy and matter exchange.
The specific heat of a substance is the amount of energy required to raise the temperature of one kilogram of that substance by one degree Kelvin or Celsius , if you're not in a laboratory. The latent heat of a substance is the heat required for an object to change states, also called a phase change. Generally speaking, values for latent heats are much higher than those for specific heat. This is also referred to as enthalpy.
Ice and water have enormous latent heats associated with them, which is why snow takes so long to melt and water is used for cooking. This is also important in keeping our planet comfortable to live on, and provides a fair amount of resistance to climate change.
This shows that any energy added by heat to a system is either converted into work or stored as internal energy. We often think about thermodynamics as being useful for inventing or testing machinery, such as engines or steam turbines. However, thermodynamics also applies to living systems, such as our own bodies.
This forms the basis of the biological thermodynamics Figure Life itself depends on the biological transfer of energy. Through photosynthesis, plants absorb solar energy from the sun and use this energy to convert carbon dioxide and water into glucose and oxygen. Photosynthesis takes in one form of energy—light—and converts it into another form—chemical potential energy glucose and other carbohydrates. Metabolism is an interesting example of the first law of thermodynamics in action.
Eating increases the internal energy of the body by adding chemical potential energy; this is an unromantic view of a good burrito. The body metabolizes all the food we consume. Basically, metabolism is an oxidation process in which the chemical potential energy of food is released. This implies that food input is in the form of work. Exercise helps you lose weight, because it provides energy transfer from your body by both heat and work and raises your metabolic rate even when you are at rest.
Biological thermodynamics also involves the study of transductions between cells and living organisms. Transduction is a process where genetic material—DNA—is transferred from one cell to another. This often occurs during a viral infection e. Once enough cells become infected, you begin to feel the effects of the virus flu symptoms—muscle weakness, coughing, and congestion. Energy is transferred along with the genetic material and so obeys the first law of thermodynamics.
Energy is transferred—not created or destroyed—in the process. When a cell does work or loses heat, its internal energy decreases. If the amount of work done by a cell is the same as the amount of energy transferred in by heat, or the amount of work performed on a cell matches the amount of energy transferred out by heat, there will be no net change in internal energy.
Based on what you know about heat transfer and the first law of thermodynamics, do you need to eat more or less to maintain a constant weight in colder weather? Explain why. Suppose Later, heat transfers You must first calculate the net heat and net work. The net heat is the transfer into the system by heat minus the transfer out of the system by heat, or. The total work is the work done by the system minus the work done on the system, or.
The change in internal energy is given by the first law of thermodynamics. A different way to solve this problem is to find the change in internal energy for each of the two steps separately and then add the two changes to get the total change in internal energy.
This approach would look as follows:. For No matter whether you look at the overall process or break it into steps, the change in internal energy is the same. What is the change in the internal energy of a system when a total of A very different process in this second worked example produces the same 9.
The system ends up in the same state in both problems. For example, a steam turbine can convert heat to kinetic energy to run a generator that converts kinetic energy to electrical energy.
A light bulb can convert this electrical energy to electromagnetic radiation light , which, when absorbed by a surface, is converted back into heat. The amount of heat transferred by a substance depends on the speed and number of atoms or molecules in motion, according to Energy Education.
The faster the atoms or molecules move, the higher the temperature, and the more atoms or molecules that are in motion, the greater the quantity of heat they transfer. Temperature is "a measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale," according to the American Heritage Dictionary.
The most commonly used temperature scale is Celsius, which is based on the freezing and boiling points of water, assigning respective values of 0 degrees C and degrees C. The Fahrenheit scale is also based on the freezing and boiling points of water which have assigned values of 32 F and F, respectively. Scientists worldwide, however, use the Kelvin K with no degree sign scale, named after William Thomson, 1st Baron Kelvin , because it works in calculations.
This scale uses the same increment as the Celsius scale, i. However, the Kelvin scale starts at absolute zero, the temperature at which there is a total absence of heat energy and all molecular motion stops. A temperature of 0 K is equal to minus The amount of heat required to increase the temperature of a certain mass of a substance by a certain amount is called specific heat, or specific heat capacity, according to Wolfram Research.
The conventional unit for this is calories per gram per kelvin. The calorie is defined as the amount of heat energy required to raise the temperature of 1 gram of water at 4 C by 1 degree. The specific heat of a metal depends almost entirely on the number of atoms in the sample, not its mass. For instance, a kilogram of aluminum can absorb about seven times more heat than a kilogram of lead.
However, lead atoms can absorb only about 8 percent more heat than an equal number of aluminum atoms. A given mass of water, however, can absorb nearly five times as much heat as an equal mass of aluminum. The specific heat of a gas is more complex and depends on whether it is measured at constant pressure or constant volume.
The unit for k is watts W per meter m per kelvin K. This property makes these materials useful for automobile radiators and cooling fins for computer chips because they can carry away heat quickly and exchange it with the environment.
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