Final answer:
The sprinter's acceleration is 9.55 m/s², calculated using Newton's second law. The work done is 0, as there is no displacement during the exertion of force at the starting moment in a foot race.
Step-by-step explanation:
To calculate the acceleration of the sprinter, we apply Newton's second law, which states that force equals mass times acceleration (F = ma). Given the average force exerted (F) is 630 N and the mass (m) of the sprinter is 66 kg, we can rearrange the formula to find acceleration (a) as a = F/m. Plugging in the values, we get a = 630 N / 66 kg, resulting in an acceleration of 9.55 m/s2.
The work done by the sprinter is calculated using the formula Work = Force x Displacement x Cosine of the angle between the force and displacement. Since the sprinter is pushing backward which is the opposite direction of the displacement, the angle is 180 degrees, and cos(180) is -1, indicating the displacement and force are in opposite directions. Thus, the work done is 0, because, during the start, the sprinter hasn't moved yet (displacement is 0), and work is dependent on the displacement.