Question 3

Both velocity and speed change.

As the runner crosses the finish line and slows to a stop, both their speed and velocity are affected. Speed decreases as the runner slows down, and since velocity includes direction, it also changes when the runner stops.

A) Velocity changes, but speed does not.

This option is incorrect because while velocity does change as the runner comes to a stop, speed also decreases. The assertion that speed remains constant contradicts the scenario where the runner slows down.

B) Both velocity and speed change.

This option is correct. As the runner jogs and then slows to a stop, their speed decreases from a positive value to zero, and their velocity, which is dependent on both speed and direction, also changes accordingly as they come to a halt.

C) Neither speed nor velocity changes.

This option is incorrect. The runner's speed decreases as they slow down, which directly impacts their velocity as well. Therefore, it is not accurate to state that neither speed nor velocity changes.

D) Speed changes, but velocity does not.

This option is incorrect because it suggests that while the runner's speed decreases, their velocity remains constant. Since velocity is a vector quantity that includes both speed and direction, it must change when the runner stops.

Conclusion

The correct answer is that both velocity and speed change, as the runner decreases their speed to a stop, directly affecting both quantities. Other options fail to recognize that speed and velocity are interrelated and both are influenced by the runner's actions. Thus, only option B accurately reflects the situation.