Explanation

Coal, gas, and oil are all examples of fossil fuels, which are energy resources formed from the remains of ancient plants and animals over millions of years.

Fossil fuels are non-renewable sources of energy.

Additional Information:

• Tidal energy is energy generated from ocean tides
• Nuclear energy is energy generated from the nucleus of atoms
• Biomass energy is energy generated from organic matter (plants, wood, waste)

Explanation

Nuclear energy is the energy released from the nucleus of an atom, either through fission (splitting of atoms) or fusion (combination of atoms).

This energy is released in the form of heat and radiation, and is harnessed in nuclear power plants to generate electricity.

Key Points:

• Solar energy is energy from the sun
• Geothermal energy is energy from the Earth's internal heat
• Tidal energy is energy from ocean tides

Explanation

The potential energy (PE) of an object is calculated as:

PE = mass x gravity x height

= 1 kg x 10 m/s^2 x 1 m

= 10 Joule

So, the energy possessed by the body is 10 Joule.

Explanation

The kinetic energy (K.E) of an object is calculated as:

• K.E = (1/2) x mass x velocity^2
• = (1/2) x 1 kg x (1 m/s)^2
• = 0.5 Joule
• = 1/2 Joule

So, the kinetic energy of the body is 1/2 Joule or 0.5 Joule.

Explanation

The work done on an object is calculated as the product of the force applied and the distance over which the force is applied:

Work = Force x Distance

= 6 N x 2 m

= 12 J

So, the work done is 12 Joule.

Explanation

When a gas changes into a liquid, the molecules:

• Move closer together (their distance decreases)
• Lose kinetic energy (they slow down)

Explanation

Evaporation is the process by which molecules escape from the surface of a liquid to become vapor, even if the liquid is below its boiling point.

This occurs when some molecules have enough energy to break free from the surface tension of the liquid and turn into vapor.

Key Points:

• Boiling occurs when a liquid is heated to its boiling point, causing bubbles to form and rise to the surface.
• Condensation is the process by which vapor is converted back into a liquid.
• Convection is the transfer of heat through the movement of fluids.

Explanation

When a gas is heated in a container of fixed volume, the molecules of the gas:

• Move faster (their kinetic energy increases, causing them to move more rapidly)
• Collide more frequently with the container walls (resulting in increased pressure)
• Do not expand (the container volume is fixed)
• Do not move further apart (the density of the gas remains the same, as the volume

Explanation

When a gas is heated in a sealed cylinder:

• The temperature of the gas increases (by definition of heating).
• The average kinetic energy of the particles increases (as the temperature rises, the molecules move faster).
• The pressure inside the container increases (as the molecules move faster and collide more frequently with the container walls).

Explanation

According to the kinetic molecular theory, the pressure exerted by a gas is caused by the bombardment of gas molecules on the walls of the container.

The gas molecules are in constant motion, colliding with each other and the container walls, resulting in a force exerted on the walls.

This force is what we experience as pressure.