Peoples Physics Concepts

3.2. Velocity http://www.ck12.org

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/379

Simulation

• http://simulations.ck12.org/RelativeVelocity/

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1. If a river is flowing south at 4 m/s and you swim straight across (i.e. east) at 2 m/s; admittedly, you’re going
   to drift a bit south. That said, calculate that distance that you drifted south from your starting point. The river
   is 16 m wide.


2. If a river is flowing south at 3 m/s and you swim at an angle of 30 degrees north of directly east at 1 m/s, how
   far did you drift up or down stream from your starting point once you reach the other side? The river is 10 m
   wide.


3. If a river is flowing north at 2 m/s and you can swim at 4 m/s, what angle should you swim at such that you
   arrive directly across the river (i.e. no drift north or south from starting point on other side)? The river is 10 m
   wide.


4. If a river is flowing south at 5 m/s and you can swim at 4 m/s maximum, is it possible to arrive directly across?
   Why or why not?

Answers to Selected Problems

1. 32 m


2. 28.9 m south of starting point


3. 30 degrees


4. No, even if you swim directly north the river will still take you south at 1 m/s