A flywheel flows from 250rpm to 150rpm in 4.2 seconds. How many revolutions occur during this time

7revolutions

Explanation:

Given parameters:

Initial revolution  = 250rpm

Final revolution  = 150rpm

Time  = 4.2s

Unknown:

Number of revolutions that occur at this time = ?

Solution:

To solve this problem;

 let us find the change in revolution  = 250rpm - 150rpm  = 100rpm

Convert the time to seconds;

         60s makes 1 minute

        4.2s will make   = 0.07min

So;

      The number of revolutions at this time  = 100rpm x 0.07min

         =   7revolutions

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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