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# Thermodynamics

What is thermodynamics?

Newtonian mechanics explain the phenomena on a larger scale such as the motion of cars. Thermodynamics is the study of the concept of heat and temperature. When heated, the size of the object will change.

Thermometers

They are devices used to measure the temperature of a system. Thermometers measure the change in physical properties associated with temperature.

• The volume of the gas expands when exposed to higher temperatures.
• The state of a solid expands when heated.
• The change in pressure of a gas will affect its volume.
• The change in volume of a gas at constant pressure.

The most common thermometer used consists of mercury that expands into a capillary tube when exposed to heat.

Thermal expansion of solids and liquids (simply: expansion because of change in temperature such as mercury being heated)

The thermal expansion of an object is the result of the change in temperature, the atoms and molecules separate as it is being heated thus the object expands.

Consider a crystalline solid,  at an ordinary temperature the atoms vibrate at equilibrium positions. A the temperature of the solid increases, the spaces between the atoms increases and the atoms vibrate at higher amplitudes. The solid increases in dimensions.

The Laws of thermodynamic

In thermodynamics, one should be careful and understand the system under consideration. A system is whatever you decide to focus on and its surroundings is whatever interacts with the system.

The zeroth law of thermodynamics

If an object A and B are separately in thermal equilibrium with an object C, then A and B will be in thermal equilibrium.

The first law of thermodynamics

It is the generalization of the law of conservation of mechanical energy.  The mechanical energy of a system is conserved in the absence of non-conservative forces.

Entropy

A disorderly arrangement is more probable than an orderly one.  An isolated system tends to favour disorder and entropy  is a measure of that disorder.

“Available energy is the main object at stake in the struggle for existence and the evolution of the world.”

Ludwig Boltzmann

# Newtonian Mechanics

## Newtonian mechanics

It was formulated using Newton’s laws of motion and describes the motion of larger bodies (compared to atoms) and moves at speeds that are much less than that of light.

Isaac Newton is one of the greatest scientist and his genius was discovered in his early twenties when he formulated the law of gravitation, invented calculus and proposed a new theory of light that would influence the scientists of modern physics.

What causes motion?

When you push or pull an object, you exert a force on it. Although forces can cause motion, it does not necessary follow the force acting on the object. The change in velocity of an object is the result of force. If an object moves at constant velocity, no force is required to maintain that motion. If several forces act on an object, the object will accelerate if the net force acting on the object is not equal to zero. Objects can change shape when a force is applied. such as stretching a rubber band.

Newton’s laws of  motion

• Newton’s first law of motion: An object at rest will remain at rest and an object in motion will continue in motion unless it experiences a resultant force.
• Newton’s second law of motion: The acceleration of an object is directly proportional to the resultant force and inversely proportional to its mass. The direction of the acceleration is in the direction of the resultant force.
• Newton’s third law of motion: If two objects interact, the force exerted on the fist object is equal in magnitude and opposite in direction to the force exerted on the second object. 