To analyze the options provided, let's consider the conditions when a runner is accelerating along a flat race track:
- The normal force exerted by the ground on the runner balances the gravitational force when the runner is not in vertical motion (which they are not on a flat track).
- The running force is the force exerted by the runner against the ground to propel themselves forward, and the resulting acceleration implies there are other forces at play as well, such as drag from the air.
Now let’s consider each statement:
A. The normal force of the ground on the runner is greater than the gravitational force of the runner on the ground.
- This is false. For a runner moving horizontally at a constant speed or accelerating, the normal force equals the gravitational force.
B. The drag on the runner from the air is greater than the running force provided by the runner.
- This is also false. If the runner is accelerating, the running force must be greater than drag; otherwise, they would not be speeding up.
C. The gravitational force of the runner on the ground is greater than the normal force of the ground on the runner.
- This is false because, on a flat surface, the normal force and the gravitational force are equal.
D. The running force provided by the runner is greater than the drag on the runner from the air.
- This is true. If the runner is accelerating, they must be applying more force through their running than the drag acting against them.
Thus, the correct answer is D. The running force provided by the runner is greater than the drag on the runner from the air.
2 answers