Sound is considered as a form of energy because it obeys the First Law of Thermodynamics which states that energy can neither be created nor destroyed but it changes from one form to another. Sound energy is produced when an object vibrates. The sound vibrations cause waves of pressure that travel through a medium, such as air, water, wood or metal. Sound energy is a form of mechanical energy.

Fuels that burns without smoke are also termed as smokeless fuels. Smokeless fuels include charcoal, liquid petroleum, biogas, coke and anthracite.

Flowing water is a good source of energy. It is available at many places and has great energy providing capability.

Coal is a conventional source of energy.

Out of the given energy sources, methane gas and petroleum are too highly combustible fuels to be used for domestic purposes. Natural gas is safer than the other two fuels and is less hazardous too.

Solar energy is potentially an excellent source of energy and if utilized properly, it can provide energy solutions for many generations to come.

A situation where the demand for the energy exceeds its availability or the supply resulting in a bottleneck effect, an increase in prices etc., is known as the energy crisis.

Energy can neither be created nor be destroyed. It can only be transformed form one form to the another. Energy once used up cannot be reversed to its original form.

Examples of conventional sources : wood, coal, fossil fuels.

Hotspots are the volcanic regions near the mantle of Earth.It is the sources of geothermal energy also called natural thermal geysers used to harness electricity.

Natural gas is a naturally occurring, flammable gas comprising largely of methane and other hydrocarbons. It is a source of fuel and formed underground.

A pinhole camera is a simple camera without a lens but with a tiny aperture. A pinhole is effectively a light proof box with a small hole in one side. Light from a scene passes through the aperture and projects an invested image on the opposite side of the box.
The image of a pinhole camera may be projected onto a translucent screen for real time viewing.

Kinetic energy,

Wind is a beneficial resource because it is a no-emissions energy source, so it produces no air or water pollution. Its operational costs are pretty low as wind is free. Wind energy is very efficient. Wind power is considered as a renewable energy resource. This means that the power generated from wind is replenished by the environment over relatively short periods of time.

The first windmill used for the production of electric power was built in Scotland in July 1887. It was built by Prof James Blyth of Anderson's College, Glasgow. Its height was 10 metres. Wind turbine was installed in the garden of his holiday cottage. It was used to charge accumulators developed by the Frenchman Camille Alphonse Faure, to power the lighting in the cottage. 

Solar-powered photovoltaic (PV) panels convert the sun's rays into electricity by exciting electrons in silicon cells using the photons of light from the sun. This electricity can then be used to supply renewable energy to your home or business. Light striking a silicon semiconductor causes electrons to flow, creating electricity. Solar power generating systems take advantage of this property to convert sunlight directly into electrical energy. 

Plants trap the solar energy and convert it into chemical energy by the process of photosynthesis.This chemical energy in the form of carbohydrates or sugar is used as food.

Solar energy is the renewable source of energy which is essential for all living beings.All plant life needs solar energy to prepare their food by photosynthesis and the animal life is dependent on plants directly or indirectly.So it is the prime source of energy.

The Sun is the primary source of energy for Earth's climate system is the first of seven Essential Principles of Climate Sciences. Principle 1 sets the stage for understanding Earth's climate system and energy balance. The Sun warms the planet, drives the hydrologic cycle, and makes life on Earth possible.Each second, more than four million tonnes of matter are converted into energy within the Sun's core, producing neutrinos and solar radiation.

The forms of energy from the sun are heat and light.

Compact fluorescent light bulbs are used in place of incandescent bulb because they use about 1/7 of the power used by the incandescent bulb. Hence, they are highly efficient in saving electricity.

$the\quad avarage\quad KE\quad of\quad n\quad moles\quad of\quad gas\quad at\quad temp\quad T\quad is\quad \dfrac { 3 }{ 2 } nRT\ when\quad temp\quad is\quad doubled\quad \dfrac { 3 }{ 2 } nR(2T)=2\times \dfrac { 3 }{ 2 } nRT\ so\quad KE\quad doubles$

A point where entire mass of the body is assumed to be concentrated is called center of mass. This point may or may be inside body or outside.

By work energy theorem,

Every substance has energy due to its mass$:$

$R = \dfrac{{mv}}{{qB}} = \dfrac{{\sqrt {2mk} }}{{qB}}{K _p} = \dfrac{{{q^2}{B^2}R _p^2}}{{2mp}}$

First we will calculate the Magnitude of velocity  so $v=\sqrt{3^2+4^2}=5\ m/s$

As the magnetic forces due to motion of electron and proton act in a direction perpendicular to the direction of motion, no work is done by these forces. That is why one ignores the magnetic force of one particle on another.

Support car moves a distance dx at a distance x.

According to de Broglie equation,Wavelength associated with an electron through potential difference V is given as

$\lambda =\frac { 12.27 }{ \sqrt { V }  } A=\frac { 12.27 }{ \sqrt { 100 }  } A=\frac { 12.27 }{ 10 } A=1.227A$

According to definition of system of particles