Two identical cylinders with a movable piston contain 0.7 mol of helium gas at a temperature of 300 K. The temperature of the gas in the first cylinder is increased to 412 K at constant volume by doing work W1 and transferring energy Q1 by heat. The temperature of the gas in the second cylinder is increased to 412 K at constant pressure by doing work W2 while transferring energy Q2 by heat. Required:
Find ÎEint, 1, Q1, and W1 for the process at constant volume.

ΔE,₁ = 977.7 J , Q₁ = 977.7 J and W₁ = 0 J

Explanation:

Given the data in the question;

T = 300 K, T = 412 K, n = 0.7 mol

since helium is monoatomic;

Cv = (3/2)R, Cp = (5/2)R

W₁ = 0 J [ at constant volume or ΔV = 0]

Now for the first cylinder; from the first law of thermodynamics;

Q₁ = ΔE,₁ +  W₁

Q₁ = ΔE,₁ = n × Cv × ΔT

we substitute  

Q₁ = ΔE,₁ = 0.7 × ( 3/2 )8.314 × ( 412 - 300 )

Q₁ = ΔE,₁ = 0.7 × 12.471 × 112

Q₁ = ΔE,₁ = 977.7 J

Therefore, ΔE,₁ = 977.7 J , Q₁ = 977.7 J and W₁ = 0 J

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.