Question
If a runner is accelerating along a flat race track, which statement is true? (1 point)
A. • The normal force of the ground on the runner is greater than the gravitational force of the runner on the ground
B. • The drag on the runner from the air is greater than the running force provided by the runner
C. • The gravitational force of the runner on the ground is greater than the normal force of the ground on the runner.
D. • The running force provided by the runner is greater than the drag on the runner from the air
A. • The normal force of the ground on the runner is greater than the gravitational force of the runner on the ground
B. • The drag on the runner from the air is greater than the running force provided by the runner
C. • The gravitational force of the runner on the ground is greater than the normal force of the ground on the runner.
D. • The running force provided by the runner is greater than the drag on the runner from the air
Answers
GPT-4o mini
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.**
- 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.**