Question

2. A fish swims north at 0.25 m/s for 3.0 seconds, stops for 2.0 seconds, and then swims south at 0.50 m/s for 4.0 seconds. Draw a position-time graph of the fish's motion, using north as the positive direction.

Answer 1

First, find the position after each period. Use the formula d = v*t.

0.25 m/s North for 3.0 seconds.

$d=0.25(\frac{m}{s})\cdot3\sec =0.75m$

When it stops for 2 seconds, the position remains constant, so we draw a horizontal line there.

0.50 m/s for 4.0 seconds.

$d=0.50(\frac{m}{s})\cdot2\sec =1m$

Basically, the fish swims 0.75 meters North and 1 meter South.