Final answer:
The grinding wheel made approximately 15.9 revolutions.
Step-by-step explanation:
To find the number of revolutions made by the grinding wheel, we need to convert the given angular velocity to revolutions per unit time.
The formula to convert angular velocity (ω) to revolutions per second (rps) is rps = ω / (2π).
Plugging in the given angular velocity of 20 rad/s, we get rps = 20 / (2π) ≈ 3.18 rps.
Since the wheel takes 5 seconds to attain this angular velocity, we can multiply the revolutions per second by the time to get the number of revolutions: 3.18 rps × 5 seconds = 15.9 revolutions.
Therefore, the number of revolutions made by the grinding wheel is approximately 15.9, which is closest to option b. 15.