A high-speed drill rotating ccw at 2400 rpm comes to a halt in 2.5 s. What is the magnitude of the drill’s angular acceleration? How many revolutions does it make as it stops?

The magnitude of the drills angular acceleration is .

The drill makes 50 revolutions before it stops.

Explanation:

The revolutions that the drill makes in 1 second is

And the angular velocity is

         (one revolution is radians)

Now, the drill comes to a halt in 2.5 s, which means the magnitude of it's angular acceleration is

In other words, the magnitude of the angular acceleration is

Now, we find the angular displacement of the drill which is given by the equation

putting in , , and , we get:

which is

               (one revolution is radians)

50 revolutions.

In other words ,the drill makes 50 revolutions before it stops.

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