How can we Increase the internal Energy
1) By heating
When we here! A substance, energy associated with its atoms are molecules is • increased. i.e., heat is converted to internal energy.
2) By doing mechanical work
When two objects are rubbed together, their internal energy increases because mechanical work: The increase in temperature the object indicates an increase in the internal energy.
Similarly, when an object slides over any surface and comes to rest because of frictional forces, the. Mechanical work- done on or by the system we partially converted into internal energy.
Internal energy is a state function
In thermodynamics, internal energy is a function of the state. Consequently, it does not depend on the path but•depends on the initial and final rules of the system.
Consider a system which undergoes a pressure and volume change from Paan . Vato Pb and Vb respectiüely, regardless of the proceés by which the system changes from initial to final state. By experiment, it has been seen that the change internal energy is always the same and is indeöendent of the paths and C2. – civil power is similar to the gravitational P.E. So like the gravitational P.E we take the change in internal energy and not its absolute value which is essential.