Molecular Physics | Thermodynamics Answers

A material has a heat capacity at constant volume C that is unchanging over a wide temperature
range. Two identical bodies made of this material, at initial temperature T and 9T, respectively, are
used to drive a heat engine. The maximum amount of work that can be obtained from this engine is

The bay radio masts are 150 m long and are made of steel. How much longer are they in the summer heat at +30 ° C than in the winter frost at -30 ° C?

How many Joules of energy are required to change 10 gram of ice at -2 οC to water at 20 οC?

A piston-cylinder device contains 6 kg of refrigerant-134a at 800 kPa
and 50oC. The refrigerant is now cooled at constant pressure until it
exist as a liquid at 24oC. Show the process on T-v diagram and
determine the heat loss from the system. State any assumption made.

QUES : - find the volume of the water dis placed and position of centre of buoyancy for a wooden block of width 2.5m and of Depth 1.5m when it floats horizontally in water the density of the all wooden block is 650kg/m3 and its length 6m.

Three liquids are at temperatures of 12 ◦C,
25◦C, and 38◦C, respectively. Equal masses of
the first two liquids are mixed, and the equilibrium temperature is 15◦C. Equal masses of
the second and third are then mixed, and the
the equilibrium temperature is 30.5
◦C.
Find the equilibrium temperature when
equal masses of the first and third are mixed.
Answer in units of ◦C.

An example of the first law of thermodynamics in our daily life’s applies
search ONE example to which The First law of Thermodynamics in our daily life applies.
1. Name the specific energy that applies to your example.
2. Explain the conservation of energy according to the First law of Thermodynamics in your example.

A poker iron has one end in a fire of temperature T = 500° C. The other end is at 26° C. Its length is 1.2 m and is radius is 5 x 10-3 m. How much heat, Q, is conducted from one end of the poker to the other in 10 s? kiron = 79 (J/s∙m∙°C)

A 1-kg block of ice is at -15° C. 4 x 105 J of heat is added to the ice block. NOTE: (a) should be divided into two parts: how much heat is needed to raise the temperature of the ice to 0 °C, and how much heat is required to melt it; then compare that sum total to 4.0 x 105 J (the specific heat to use for ice is provided in the accompanying sheet to this homework)

(a) Does it fully melt?
(b) What is the final overall temperature?

1. A 1000-kg block of ice melts in an arctic lake. The ice is at 0° C. The lake is initially at 10° C and cools to 5° C after the ice melts.
(a) What is the mass of the water in the lake?
(b) What is the heat lost by the lake due to the block of ice melting?