Mechanics

Overview of types of physical quantities
Differentiating between a vector quantity and a scalar quantity is essential in IB Physics. There are several different types of vector quantities as well as scalar quantities. A few types of scalar quantities include: speed, distance, mass, time, brightness, energy, volume, and density. One thing common amongst all these types of quantities is that they all measure only a size/ magnitude. E.g. Mass measures the amount of matter within an object. There is no indication of a direction and only an indication of a size.

Types of vector quantities on the other hand include a direction with a magnitude/ size. A few types of vector quantities include: velocity, displacement, acceleration, force (weight, frictional force, normal force, etc.) and torque. One thing common amongs these types of quantities is that they all have direction. E.g. Weight (gravitational force) is a downward force acting upon an object. In a free body diagram (will be discussed in later pages) a downward arrow would be shown below an object to illustrate a gravitational force.

Notation for Vectors and Scalars

For scalars, we simply indicate a letter to show the unit for a type of scalar quantity. E.g. For speed, it will be indicated with an "v". But for vectors, there can be three ways we can indicate a unit is a vector type. E.g. Velocity, the vector version of speed (because it has direction indicated) can be shown as a "v" with an arrow head on top of the "v". In IB though, the way to indicate a unit is a vector is by bolding the letter. E.g. "v"

All questions on the IB exam will show vectors being bolded and scalars not being bolded.