Relative Motion in 2-D

Dave Nero


This simulation shows the relative motions of a boat, a body of water, and the shore as viewed from different reference points. Drag to adjust the velocity vectors of the boat and the water. Use the drop down list to change how the vectors are drawn. Check "Show Vector Addition" to show with dashed lines how all of the vectors can be represented as vector sums and difference of the two velocities that you set. Click the button in the bottom left corner to animate the scene. Click it again to pause. You can change the settings while the animation plays. Click the reset icon in the top right corner to reset the scene. "w.r.t." stands for "with respect to."
  1. Can you identify where each vector comes from?
  2. What combination of velocities of the boat and water make the boat be at rest with respect to the shore? In this case, is the boat also at rest with respect to the water?
  3. Click the play icon. Can you predict how everything will move as you change reference frames?