Explanation:
At night, when that part of Earth is facing away from the sun, space looks black because there 8s no nearby bright source of light like the sun , to be scattered
Answer:
Part(a): The value of the spring constant is
.
Part(b): The work done by the variable force that stretches the collagen is
.
Explanation:
Part(a):
If '
' be the force constant and if due the application of a force '
' on the collagen '
' be it's increase in length, then from Hook's law

Also, Young's modulus of a material is given by

where '
' is the area of the material and '
' is the length.
Comparing equation (
) and (
) we can write

Here, we have to consider only the circular surface of the collagen as force is applied only perpendicular to this surface.
Substituting the given values in equation (
), we have

Part(b):
We know the amount of work done (
) on the collagen is stored as a potential energy (
) within it. Now, the amount of work done by the variable force that stretches the collagen can be written as

Substituting all the values, we can write

Convection is the process in which heat is transferred by movement of a heated fluid such as air or water. Natural convection results from the tendency of most fluids to expand when heated so it becomes less dense and rise above.
For example- In a pot of water on a stove the liquid t bottom is heated by conduction. The hot water has lower density and it rises above pushing the cold water downwards so it gets heated.
It might be a low pressure