A book has a mass of 50 grams and an
acceleration of 5 m/s/s. What is the
force on the book?

From second law of motion, we have,

F = ma

So, F = 50kg × 5m/s^2 = 250 kg m s^-2 = 250 N

v=ir = 3x15 =45 v

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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