Explanation

• The shortest distance between two points is called displacement.
• Displacement is a measure of the straight-line distance between two points.
•  It is a scalar quantity.

Key Point: The longest distance between two points is called the circumference (if the points are on a circle) or a diagonal (if the points are on a polygon or a rectangle).

Explanation

The moon is a satellite because it moves around Earth.

Earth and the moon are called "natural" satellites.

ND5-07-2023

Explanation

The melting point of ice at normal atmospheric pressure is 0 °C (zero degrees Celsius).

Key Points:

• 0 K (zero Kelvin) is equivalent to -273.15 °C, which is absolute zero, the lowest possible temperature.
• 100 °C is the boiling point of water at normal atmospheric pressure.

Explanation

Solar and wind energy are renewable sources of energy, meaning they are sustainable and will not run out.

Solar energy is generated from the sun's rays.

Wind energy is generated from the wind.

Explanation

The quantity of matter in a body is called its mass.

Explanation

Weight is a vector quantity because it has both magnitude (amount of force) and direction (downward, towards the center of the Earth).

Explanation

The law of conservation of momentum states that the total momentum of a closed system (such as a system of two bodies) remains constant over time, as long as there are no external forces acting on the system.

This means that the total momentum before a collision is equal to the total momentum after the collision.

Explanation

Scalar quantities are physical quantities that have only magnitude (amount or size) but no direction.

Examples of scalar quantities include:

• Mass
• Temperature
• Time
• Energy
• Distance

Explanation

A body is in equilibrium when the net force acting on it is zero, and it is not changing its motion.

This means that the body is either at rest or moving with a constant velocity (uniform speed), but not accelerating.

Explanation

The SI unit of velocity is a ms^-1 and m/s.