Final answer:
The net external force on Andrea, a 67.0-kg sprinter starting with an acceleration of 4.35 m/s², is 291.45 newtons.
Step-by-step explanation:
The question at hand requires the application of Newton's Second Law of motion which states that the net external force acting on an object is equal to the product of its mass and acceleration (F = ma). In this case, we are given that Andrea, a 67.0-kg sprinter, starts a race with an acceleration of 4.35 m/s². To calculate the net external force on her, we multiply her mass by the acceleration.
Force = Mass × Acceleration
Force = 67.0 kg × 4.35 m/s²
Force = 291.45 N
Therefore, the net external force acting on Andrea is 291.45 newtons.