Two Ships — Collision Watch

See how the orange ship moves for an observer aboard the blue ship.

Switch from Ground to Object A: A stops, while B moves with relative velocity.

2D Relative Velocity Lab

Add and subtract velocity vectors by components.

Real-world example

Reference frame

Watch how separation changes.

0.0relative vx

0.0relative vy

0.0relative speed

vB relative A = vB − vA

The relative vector predicts B's path in A's frame.

Object A ground speed8.0 m/s

Object A heading0°

Object B ground speed10.0 m/s

Object B heading270°

Simulation speed1×

Blue is vA, orange is vB, and purple is vB − vA. It runs from the tip of vA to the tip of vB.

Teacher / Demo mode

Relative velocity requires two moving objects and a named observer.

Object A has ground velocity vA. Object B has ground velocity vB. Each has an east–west and north–south component.

Subtract A's velocity from everything. A's velocity becomes zero.

vB relative A = vB − vA

relative vx = vBx − vAx

relative vy = vBy − vAy

The purple vector is the velocity B actually has in A's moving frame.

relative position later = starting separation + relative velocity × time

If the relative path passes through A, the objects meet. Otherwise it predicts closest approach.

Score: 0 / 7