A reversible engine works between between two
temperatures whose difference is 100°C. If it
absorbs 746 J of heat from the source and rejects
546 J to the sink, calculate the temperature of the
source and the sink.
A) 100°C, 20°C
B) 100°C, 0°C
C) 80°C, 0°C
D) 80°C, 20°C

this is poiselle's equation from fluid mechanic in physics. mech eng

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this

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.