The amount of work done by two boys who apply 310 n of force in an unsuccessful attempt to move a stalled car is

1. 310 n · m.
2. 620 n.
3. 310 n.
4. 0.5.620 n · m

0 N-m

Explanation:

Given

Force applied is given by

It is given that there is no movement of car

therefore Net displacement is zero i.e.

Work done is given by

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.

the answer should be in the picture.