Final answer:
The magnitude of the centripetal acceleration for a rock swung in a circle with a speed of 10 m/s and a radius of 2.1 m is calculated using the formula a = v²/r, giving a magnitude of 47.6 m/s².
Step-by-step explanation:
When a rock is swung in a circle with a constant speed, it experiences what is known as centripetal acceleration. This is the acceleration that acts on an object moving in a circular path and is directed towards the center of the circle. To calculate the magnitude of this acceleration, we use the formula a = v²/r, where v is the speed and r is the radius of the circle.
In this case, the speed v is 10 m/s and the radius r is 2.1 m. Plugging these values into the formula gives us:
a = (10 m/s)² / (2.1 m) = 100 m²/s² / 2.1 m = 47.62 m/s²
This means the correct answer to the question, "What is the magnitude of the acceleration?", would be 47.6 m/s² which is option C.