Question

a man runs east at 6.6m/s, for 13s, stops for 2.7s, then runs back west at 4.4m/s for 4.0s. what is the mans avergae velocity

Answer 1

Answer: 3.46 m/s

Explanation: Change in displacement( Delta x) = 6.6 m/s * 13 s + 0 m/s * 2.7 s+ 4.4 m/s * 4.0s = 85.8m - 17.6m = 68.2 m.

Note : In the cartesian coordinates, we take right side from the origin as positive and left side from the origin as negative. It's just a convention though. When you make graphs for directions it so happens that east is in the right and west in the left.

Now,

Change in time (Delta t) = 13.0 s+ 2.7 s+4.0 s = 19.7s (Note: You cannot have negative time period because time is a scalar quantity meaning that it has only magnitude and no direction.)

Therefore, Man's average velocity (V avg) = Delta x/ Delta t

= 68.2m/ 19.7 s

= 3.46 m/s