Greg drew a diagram to compare two of the fundamental forces.

A venn diagram of 2 intersecting circles with the left circle labeled gravitational force and the right circle labeled electromagnetic force. There is an X in the gravitational force circle. There is a Z in the electromagnetic force circle. There is a Y in the intersecting area.
Which labels belong in the areas marked X, Y, and Z?

X: Attractive
Y: Repulsive
Z: Infinite range
X: Infinite range
Y: Attractive
Z: Repulsive
X: Always attractive
Y: Infinite range
Z: Attractive or repulsive
X: Attractive or repulsive
Y: Infinite range
Z: Always attractive

X: Always attractive

Y: Infinite range

Z: Attractive or repulsive

ANSWER IS C

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.

this is an example of "committed" time.

committed time, as contracted time, takes need over essential and available time since it is seen as profitable work. it alludes to the time allotted to keep up a home and family. at the point when a man is commuting using committed time this individual may feel that the drive is an obligation to family, for example, strolling youngsters to class or driving a mate to work. contracted and committed time clients may feel that their commute could really compare to the commute of important or leisure time clients on the grounds that their commute is profitable work. in this manner, they might be more disposed to pick a mechanized method of movement.