Relative Motion

This interactive simulator explores Relative Motion in Classical Mechanics. Boat crossing a river, plane in wind. Vector addition visualization. Use the controls to change the scenario; watch the visualization and any graphs or readouts to connect the model with lectures, labs, and homework.

Who it's for: Best once you already know the basic definitions and want to build intuition. Typical context: Classical Mechanics.

Key terms

  • relative
  • motion
  • relative motion
  • mechanics
  • classical

Live graphs

How it works

The water moves with the river; the boat has a velocity relative to the water. The velocity seen from the shore (ground) is the vector sum of the river’s flow and the boat’s velocity through the water. Aiming straight across is not enough when the river flows — you drift downstream unless you point partly upstream.

Key equations

vrel = (vb sin θ, vbcos θ)   (θ from straight-across toward downstream)
vground = (vriver + vb sin θ,   vb cos θ)