- Thermal Energy Test The front door of a home is made of steel. When it is warm outside, the door sticks and is difficult to open or close. When the weather is cool, the door
does not stick. Which statement best explains the difference in the behavior of the door when the weather is warm compared to when it is cool?
A. When a material contracts, it increases in volume due to an increase in kinetic energy.
a
B. Different materials expand and contract at the same rates due to the kinetic energy being the same.
C. Thermal expansion makes the door fit better when it is cooler due to a decrease in kinetic energy.
D. The metal in the door expands when it becomes warm due to an increase in kinetic energy, and contracts when it's cooler.

D. The metal in the door expands when it becomes warm due to an increase in kinetic energy, and contracts when it's cooler.

Explanation:

because the metal in the door expands due to warm to an increase in kinetic energy and contracts.

d eras and periods

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.