Molecular Physics | Thermodynamics Answers

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When you take a bath, how many kilograms of cold water (10°C) must you mix with hot water

(50°C) so that the temperature of the bath is 35°C? The total mass of water is 180 kg. Ignore any

heat flow between the water and its surroundings.

What will be the change in internal energy of a system that absorbs 300 J of heat and performs 500 J of work?

Calculate the change in internal energy, 400 J of work is done on the system and the system losses 225 J of heat energy.

If the temperature of a hot reservoir is 400K, what must the exhaust temperature be so that the efficiency of an ideal heat engine is 25%?

If all the energy of a 20-g bullet travelling at 1km/s is converted into heat, how many calories are generated?

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what volume (in L) of 4.35 M CHI solutions is needed to react with 18.5 g of Ca(OH)2

1500kg of steam is to be produced per hour with an enthalpy of 3077kj/kg. The feed water supplied to the boiler has an enthalpy of 167.5 kj/kg. The velocities of the water at inlet and the steam at exist are 2m/s and 45m/s respectively. Find the rate of which heat must be supplied to the boiler.

A Carnot engine has a power output of 139 kW. The engine operates between two reservoirs at 16◦C and 658◦C.

(A)How much thermal energy is absorbed each hour? Answer in units of J

(B)How much thermal energy is lost per hour? Answer in units of J.

A CD starts from rest and accelerates to an angular frequency of 3.5 rev/s. Calculate

the disc s average period T and centripetal velocity at the edge of the disc when

radius is 2. 0 x 10^-2m. 

Assuming compression is according to the law PV = constant. Calculate the initial

volume of gas at a pressure of 2 bar which will occupy a volume of 6 m3 when it is

compressed to a pressure of 42 bar.

A sample of helium behaves as an ideal gas as it is heated at constant pressure from 253 K to 368 K. If 20 J of work is done by the gas during this process, what is the mass of the helium sample? The universal gas constant is 8.31451 J/mol · K. Answer in units of g.