What is best to say about a runner who is running at a constant velocity? a. their acceleration is positive. b. their acceleration is negative. c. their acceleration is zero. d. their acceleration cannot be determined.

The question is asking us what is BEST to say about a runner who is running at a constant velocity? A constant velocity (=speed) means that they are not getting faster or slower - they are running exactly as fast all the time. This meanst that their speed does not change, so their change of speed is equal to 0. A change of speed is called acceleration so their C. Their acceleration is zero. - C is the correct answer.

Two cars collide, lock bumpers and move together after the collision.this collision is known as perfectly inelastic collision.