Scope and excitement of physics

Before we learn about scope and excitement of physics .. let me try to help you understand what is all about physics? so that when tell you about the scope you will be able to understand in a better way.

what is physics?

The word 'Physics' comes from the Greek word 'phusis' meaning 'nature', introduced by the ancient scientist 'Aristotle'. Man has always been fascinated by nature. So, he questioned and sought answers for every phenomena nature could offer. The branch of science which is devoted to the study of nature and natural phenomena is called Physics. It is expected that all the events in nature take place according to some basic laws. Physics reveals these basic laws from day-to-day observations.

The knowledge of physics accumulated till 1900 is called classical physics that deals with macroscopic phenomena. It includes subjects like:

• Mechanics
• Thermodynamics
• Electromagnetism, and
• Optics

Scope and excitement of physics -

The scope of physics is very large. Physics deals with a wide variety of disciplines such as mechanics, heat and light. Study of mechanics helps us to know the forces involved in the flight of a bird, walk of a man and so on. The study of heat helps us to know the rise and fall of temperatures, working of heat engines and so on. Electricity helps to understand the basic principles involved in generators and motors.

This is only the brief introduction to scope and what is all about physics.. Keep reading.. i can help you more on all physics topics.

The Carnot Machine

Let us study about Carnot machine,
We consider the standard Carnot-cycle machine, which can be thought of as having a piston moving within a cylinder, and having the following characteristics:

A perfect seal, so that no atoms escape from the working fluid as the piston moves to expand or compress it.

Perfect lubrication, so that there is no friction.

An ideal-gas for the working fluid.

Perfect thermal connection at any time either to one or to none of two reservoirs, which are at two different temperatures, with perfect thermal insulation isolating it from all other heat transfers.

The piston moves back and forth repeatedly, in a cycle of alternating "isothermal" and "adiabatic" expansions and compressions, according to the PV diagram shown below:


By definition, the isothermal segments (AB and CD) occur when there is perfect thermal contact between the working fluid and one of the reservoirs, so that whatever heat is needed to maintain constant temperature will flow into or out of the working fluid, from or to the reservoir.

By definition, the adiabatic segments (BC and DA) occur when there is perfect thermal insulation between the working fluid and the rest of the universe, including both reservoirs, thereby preventing the flow of any heat into or out of the working fluid.

The isothermal curves (but not the adiabatic curves) are hyperbolas, according to PV = nRT. The enclosed area (and therefore the mechanical work done) will depend on the two temperatures ("height") and on the amount of heat transferred, which depends in turn on the extent of the isothermal compression or expansion ("width"), during which heat must be transferred to maintain the constant temperature.

We will denote the heat transferred to or from the high-temperature reservoir (during the transition between points A and B) as Qh.

We will denote the heat transferred to or from the low-temperature reservoir (during the transition between points C and D) as Qc.

Hope the above explanation helped you.

Gravitational potential energy

Let us study what is meant by potential energy,

Potential energy is the energy stored in a body or a system by virtue of its position in a field of force or by its configuration. A force acting on a body or a system can also change its potential energy.

Here we shall discuss two cases:

(i) Potential energy of a body due to gravity, called gravitational potential energy.

(ii) Potential energy of a spring when it is elongated or compressed by an external force called elastic potential energy.

Gravitational Potential Energy : On anybody (of mass m) a constant force, given by F = mg, acts. It is directed towards the earth. Here g is acceleration due to gravity.

Consider a body of mass m moving vertically downward from height y2 to y1, as shown in the Figure given below, the work done by this constant force of gravity is given by

W = -mg(y2-y1) = - (mgy2 - mgy1)

Here W depends on the difference the height or position. So we can define gravitational Potential Energy associated with the body as

U = mgy

Hence W = -(V2 - V1) = -ΔV

The negative sign implies that when gravity does positive work, the potential energy decreases. When gravity does negative work (the body moves upward), the potential energy increases.

We can observe that when a body falls from a height, it accelerates and increases its speed and hence gains K.E. This is at the expense of gravitational P.E. Hence we can relate potential energy and kinetic energy.
Hope the above explanation helped you, now let us learn expressions for potential energy