Molecular Physics | Thermodynamics Answers

A concrete walk is poured on a day when the temperature is 20°C in such a way that the ends are unable to move.
What is the stress in the cement on a hot day of 50°C? Does the concrete fracture? Take Young’s modulus for
concrete to be 7.00x 109 N/m2 and the compressive strength to be 2.00 x 109 N/m2.

A flat bottomed test tube of 200mm height and 10mm internal diameter stands on its
base. It initially contains a residue of a liquid solvent of depth 2mm, which is gradually
evaporating. The test tube is in an air filled chamber at atmospheric pressure and 27oC .
The chamber is large enough such that the concentration of the solvent in the chamber is
negligible. The molecular weight of the solvent is 32 . At 27oC the solvent’s vapour pressure is
19kPa , its liquid density is 780kg /m3 and its diffusivity in air is D = 1.2 x10−5 m2 / s

i) Neglecting variations in the height of the vapour column in the tube during
evaporation, determine how long it will take for the solvent to evaporate completely.

ii) The air pressure in the chamber is now doubled, with everything else remaining as
in part i). Determine how long it will now take for the solvent to evaporate completely.

iii) The temperature of the entire system is now raised significantly relative to the
conditions in part ii). what should happen to the solvent’s
evaporation time, and explain how this occurs by making use of the equation above.

What is the equation for work done in a reversible isothermal process (processes 1 to 3 in this case)? My course tutor wrote down (P3V3)ln(V1/V3), what is this?

Data indicates the air enters the wind turbine at average speed of 24km/h at a temperature of 10 degree celcius and a pressure of 0.9atm and has diameter of 1.25m. calculate the electrical power available ( energy equation in fluid mechanics)

A 200 gm piece of metal is heated to 150 degree and then dropped into an aluminium calorimeter of mass 500 gm , containing 500gm of water initially at 25 degree . Find the final equilibrium temperature of the system if the specific heat of metal is 128.100J/kg-K, specific heat of aluminium is 903 J/kg-K, while the specific heat of water 4200 J/kg-K

& Water flows through the double nozzle of diameters 95 mm and 75 mm . 2 the flow speed of both the nozzle gets at the outlet is 18 ms^-1 . The axis of the pipe and both the nozzles lir in a horicontal plane .
Your given that ρ = 1000Kgm^-3. Negtlect the fricational effect


A).state the continuiyu Equation for steady state flow in a circular pipr and explain its phyical meaning

B). sketch the control volume and show the directions of all relevant forces acting on the fluid

C).Determine the velocity of warer entering the control volume

D).Determine the volumetric flow rates at A, B , And C

& A hot-air balloon must support its own weight plus a person for a total weight of 1200 N Ambient air is at 20C and 1 atm . The hot air inside the balloon is at 65C and 1 atm. What diameter of spherical balloon just will support the total weight ? neglect the size of the hot-air inlet vent .

Does Maxwell distribution of speed hold for real gas?

In each cycle of a Carnot engine, 97 J of heat is
absorbed from the high-temperature reservoir
and 50 J is exhausted to the low-temperature
reservoir.
What is the efficiency of the engine?

How is heat energy trapped in a greenhouse?