When a 75.0-kg man slowly adds his weight to a vertical spring attached to the ceiling, he reaches equilibrium when the spring is stretched by 6.50 cm. (a) find the spring constant. (b) if a second, iden- tical spring is hung on the first in series, and the man again adds his weight to the system, by how much does the system of springs stretch? (c) what would be the spring constant of a single, equivalent spring?

1)

2)displacement

3)

Explanation:

At equilibrium position the weight of the man should be balanced by force in the spring

thus we have at equilibrium

Applying values we get

2)

When we add another identical spring we get an equivalent spring with spring constant as  

Applying values we get

Thus at equilibrium we have

3) Equivalent spring constant will be as calculated earlier

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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