Thermodynamics

Thermodynamics States About Energy Conversion Thermodynamics is the branch of science that embodies the principles of energy transformation in macroscopic systems. The general restrictions which experience has shown to apply to all such transformations are known as the laws of thermodynamics. These laws are primitive; they cannot be derived from anything more basic. The first law of thermodynamics states that energy is conserved; that, although it can be altered in form and transferred from one place to another, the total quantity remains constant. Thus, the first law of thermodynamics depends on the concept of energy; but, conversely, energy is an essential thermodynamic function because it allows the first law to be formulated. This coupling is characteristic of the primitive concepts of thermodynamics. The words system and surroundings are similarly coupled. A system is taken to be any object, any quantity of matter, any region, and so on, selected for study and set apart (men

Moving Object Connecting by Rope

On the below picture there are two beam A and B that connected by rope through smooth pulley and the pulley weight can be ignored. If the weight of A (Wa) bigger that the weight of B (Wb), then the beam A will moving down and beam B will upward. Because the pulley weight is ignored, as long as the system on moving the tension of both top of rope are the same, say T. The acceleration of both beam also same, say a.


On determining the equation of motion is base on the Newton Law II. On this calculation all the forces indirection with object are positive, while forces the opposite with object direction are negative.

The force resultant that work on beam A is:
Σ FA = mA x a
wA - T = mA x a

The force resultant that work on beam B is:
Σ FB = mB x a
T - wB = mB x a

By adding both above equation then we get:
wA - wB = mA x a + mB x a
and w = m x g

(mA - mB) g = (mA + mB) a

We can calculate a by using the above equation.