What is the velocity at 3 seconds? a. -3.3 m/s b. -2.0 m/s c. -0.67 m/s d. 5.0 m/s e. 7.0 m/s

Velocity = (distance covered in a direction) / (time to cover the distance)

Since the y-axis is position (distance), the speed at 3 seconds is the slope of the graph at 3 seconds, and NOT its y-value.

The slope is fairly easy to pick off, because the graph is so straight from 2 sec to 5 sec.  During that time, the distance shrinks by 10 meters (from 10m to zero).  So the slope of that whole piece of the graph is  (-10m) / (3 sec).

That's a slope of  (10/3 m/s) or 3.33 m/s .

In answer to the question, we can only give the speed at 3 sec, not the velocity, since we have no information about the direction of the motion.  Consequently, I would call the speed a positive number.  But it's not worth arguing about, so you should just select choice-A and not make a big scene.

uranium fissions/breaks up giving out energy and neutrons