Scalars and vectors

A scalar has magnitude only (mass, time, speed, energy). A vector has magnitude and direction (displacement, velocity, acceleration, force).

Components

• A vector in the plane: v = (vx, vy)
• Magnitude: |v| = sqrt(vx^2 + vy^2)
• Direction: theta = atan2(vy, vx)

Adding vectors

1. Add components separately.
2. Or place head to tail and draw the resultant.

Exam tip: in AP Physics C, unit vector notation (i, j, k) is expected in free response answers.