• Scalar Quantity: Physical quantities that only have size/magnitude but no direction. Examples include Distance, Mass, Energy. These quantities are absolute and do not rely on any direction for their definition.

  Real-world Example: If you travel 3.4 km from home to school, irrespective of the route you take, the total distance covered will remain the same i.e., 3.4 km. This is the scalar quantity  it only matters how far you have gone, not where.

• Vector Quantity: Physical quantities that have both size/magnitude and direction. Examples include Displacement, Force, Acceleration.

  Real-world Example: If you travel from home to school along a straight line of 1.7 km in a southwest direction, your displacement is "1.7 km Southwest". This is a vector quantity - it tells you not just how far you've gone, but also where.

Remember: Not all quantities with a minus sign are vectors. A negative sign may indicate direction for vectors, but it doesn't turn a scalar into a vector. For example, you can have negative money in your bank account (debt), but money is still a scalar, not a vector.

• Displacement: The change in position of an object with respect to its starting point. It requires three pieces of information to specify in three dimensions: magnitude (with unit), direction (or heading), and the change in height during the journey.

• Coordinates: Coordinates in a three-dimensional space can be given in Cartesian form (x, y, z - distances along the three axes) or in spherical form (distance r, azimuth φ from north, and elevation θ from horizontal).

  Real-world Example: Think about using GPS on your phone. It uses your latitude, longitude, and altitude (height above sea level) to locate you. This is a way of using three coordinates to describe your location.

• Distances can be measured in various units like meters, miles, kilometers, chains, light-years (astronomy), and astronomical units (distance from Earth to the Sun).

• In exams, lengths are usually expressed in multiples/sub-multiples of the meter or in well-recognized scientific units such as light-years.

  Real-world Example: When you use a map, distances may be given in miles or kilometers depending on the country you're in. Astronomers use light years to measure distances between stars, because using kilometers or miles for such immense distances would be impractical and hard to comprehend!

Remember, a solid grasp of vectors and scalars is essential for understanding Physics. They are fundamental to many physical concepts and phenomena.