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.

Explanation

A solid has a fixed shape and a definite volume, regardless of its container.

The particles (molecules, atoms, or ions) in a solid are closely packed and have a fixed position, giving the solid its rigidity and shape.

Explanation

A burning candle is an example of all three states of matter:

• Solid: The wax is in a solid state.
• Liquid: The melted wax is in a liquid state.
• Gas: The vaporized wax and combustion products are in a gaseous state.

Explanation

In a solid, the particles (atoms, molecules, or ions) are closely packed and vibrate in place, holding their position in the crystal lattice.

This vibration is due to thermal energy, and the particles oscillate around their fixed positions.

Key Points:

• In a gas, particles are widely spaced and move freely.
• In a liquid, particles are close together but move past each other.

Explanation

The velocity of a satellite is independent of its mass.

According to Kepler's laws, velocity is determined by the orbit's semi-major axis and the central body's gravitational constant (G), not by the satellite's mass.

Explanation

The critical velocity (vc) is the minimum velocity an object must have to orbit the Earth without falling to the ground.

It is given by the formula:

vc = √(gR)

where:

• g is the acceleration due to gravity (approximately 9.8 m/s²)
• R is the radius of the Earth (approximately 6,371 kilometers)

Explanation

Rockets are used to put satellites into orbit around the Earth.

Rockets provide the necessary thrust and velocity to overcome the Earth's gravitational pull and reach the desired altitude and orbit.