How is linear speed calculated in relation to circumference?

Linear speed is directly related to the distance traveled per unit of time. To understand why the answer is correct, consider that linear speed is calculated as the product of the rotational speed (in revolutions per minute) and the distance traveled in one complete rotation, which is the circumference of the circle formed by the rotating object.

In this case, when you take the revolutions per minute (rev/min) and multiply it by the circumference of the circle (which can also be expressed in terms of diameter using the formula πD), you obtain the distance traveled per minute. Dividing this result by 60 converts the measurement into a linear speed in units like meters per second or feet per second. Hence, this method effectively gives you the linear speed.

The other choices do not accurately represent the relationship between circumference and linear speed in this context. For example, multiplying time by circumference does not yield speed but rather a distance measurement, and while distance/time does define speed, it doesn't specifically address the relationship with circumference related to rotational motion. The fourth option also oversimplifies the concept by suggesting that speed is merely the circumference divided by revolutions, which does not account for the time factor necessary for proper speed calculation.