Focus Physics

1.1.7 — Determine, by calculation or graphically, the resultant of two vectors at right angles, limited to forces or velocities only

1.1.7 — Determine, by calculation or graphically, the resultant of two vectors at right angles, limited to forces or velocities only

You must be able to find the combined effect (resultant) of two perpendicular vectors, like:

  • Two forces acting at 90°
  • A boat moving across a river with a current
  • An aircraft flying with a crosswind

Method 1: Pythagoras (when vectors are at right angles)

If forces F₁ and F₂ are perpendicular:

R=F12+F22R = \sqrt{F_1^2 + F_2^2}