72. Linear Speed. A wheel with a 30-cm radius is rotat- ing at a rate of 3 radians / sec. What is the linear speed of a point on its rim, in meters per minute?​

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Explanation:

Let's find the circumference

C = 2*pi*r

C = 2*pi*30

C = 60pi

This is the exact circumference in terms of pi.

In one revolution, the point on the wheel moves forward exactly 60pi cm.

In a sense, it's "speed" is 60pi cm per revolution.

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Let's convert that speed to meters per minute as shown in the diagram below (I'm using the railroad tracks method to convert).

Note the color coding to see how the units cancel. The goal is to get meters on top and minutes down below. Also note how the "pi" terms cancel since we have on top and one down below.

After the canceled stuff goes away, we multiply straight across.

Divide the results: 10800/200 = 54

The linear speed is 54 meters per minute

This speed is exact because the 60pi figure is the exact circumference

This is the speed the point on the wheel moves, and we can say that the car itself also moves at a linear speed of 54 meters per minute.

Side note: 54 meters per minute = 2.013 mph approximately, which is a fairly slow walking speed.

hdjd

step-by-step explanation: