Scalars and Vectors

Think about the difference between saying "I walked 5 metres" versus "I walked 5 metres north" - that's the key difference between scalars and vectors! Vectors are quantities that have both magnitude (size) and direction, whilst scalars only have magnitude.

Common vector quantities include force, acceleration, momentum, displacement, and velocity. These all need direction to make sense - you can't properly describe a force without saying which way it's pushing! Meanwhile, scalar quantities like energy, mass, density, volume, distance, and speed don't need direction.

Here's a helpful memory trick: Vector from Despicable Me says he's "committing crimes with both direction and magnitude" - just like vector quantities in physics! This makes it easy to remember what vectors are all about.

When you have multiple vectors acting together, you can find the resultant vector - the single vector that has the same effect as all the others combined. You can calculate this using Pythagoras' theorem for right angles or draw a scale diagram using the parallelogram rule.

Quick Tip: If a quantity needs direction to be fully described, it's a vector. If just a number and unit are enough, it's a scalar!