Nevertheless, heat and work can produce identical results.
For example, both can cause a temperature increase.
Then the first law of thermodynamics can be used to find the change in internal energy.
In part (b), the net heat transfer and work done are given, so the equation can be used directly.
What is the net change in internal energy of the system?
(b) What is the change in internal energy of a system when a total of 150.00 J of heat transfer occurs out of (from) the system and 159.00 J of work is done on the system? Strategy In part (a), we must first find the net heat transfer and net work done from the given information.Heat transfer () and doing work () are the two everyday means of bringing energy into or taking energy out of a system. Heat transfer, a less organized process, is driven by temperature differences.Work, a quite organized process, involves a macroscopic force exerted through a distance.A second way to view the internal energy of a system is in terms of its macroscopic characteristics, which are very similar to atomic and molecular average values.Macroscopically, we define the change in internal energy to be that given by the first law of thermodynamics: Many detailed experiments have verified that , where is the change in total kinetic and potential energy of all atoms and molecules in a system.is positive for net heat transfer The first law of thermodynamics is actually the law of conservation of energy stated in a form most useful in thermodynamics.The first law gives the relationship between heat transfer, work done, and the change in internal energy of a system.This boiling tea kettle represents energy in motion.The water in the kettle is turning to water vapor because heat is being transferred from the stove to the kettle.It has also been determined experimentally that the internal energy of a system depends only on the state of the system and More specifically, is found to be a function of a few macroscopic quantities (pressure, volume, and temperature, for example), independent of past history such as whether there has been heat transfer or work done.This independence means that if we know the state of a system, we can calculate changes in its internal energy from a few macroscopic variables.