A gas sample is held at constant temperature. What happens to the pressure of the sample if the volume is doubled and the number of molecules is doubled?\

If the volume is doubled and the number of molecules is doubled, pressure is unchanged

Explanation:

Step 1: Data given

Temperature = constant

Volume will be doubled

Number of molecules will be doubles

Step 2:

p*V = n*R*T

⇒ gas constant and temperature are constant

Initial pressure = n*R*T / V

Initial pressure = 2*R*T/2

Initial pressure =  RT

Final pressure = 4*RT / 4

Final pressure = R*T

If the volume is doubled and the number of molecules is doubled, pressure is unchanged

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.