Heat Notes by Sir Waqar Hussain
Important Easy Notes of Physics of Chapter No. 11: Heat written by Professor Mr. Waqar Hussain Suib. These notes are very helpful in the preparation of Physics for students of the 12th class and these are according to the paper patterns of all Sindh Book Boards.
Summary and Contents:
Topics which are discussed in the notes are given below:
- Definition of Heat
- Definition of Temperature and Unit of temperature
- Definition of Different Temperature Scales
- Definition of Celsius Scale
- Definition of Fahrenheit Scale
- Relationship between Celsius and Fahrenheit scale
- Definition of Kelvin scale
- Law of Heat Exchange
- Thermometric Properties with example
- Thermal Expansion with explanation and Type of Thermal Expansion
- Definition of Linear Expansion with Mathematical Expression
- Definition of Volumetric Expansion and Mathematical Expression
- Relation between Coefficient of linear and volumetric expression
- Definition of Bimetallic Thermostat, Construction, Working principle.
- Kinetic Molecular Theory
- Definition of Gas Laws
- Definition of Boyles law and Graphical Representation
- General Gas Law: According to Boyle’s Law, According to Charles Law, According to Avogadro Law.
- Pressure of an Ideal Gas (Pressure Equation)
- Kinetic Energy of Molecules of an Ideal Gas
- Derivation of Gas Laws from Pressure equation
- Root Mean Square Velocity of Molecule of an Ideal Gas(𝒗𝒓𝒎𝒔)
- Definition of Heat Capacity with formula
- Definition of Specific Heat Capacity with formula
- Definition of Molar Specific Heat with formula
- DETERMINATION OF SPECIFIC HEAT CAPACITY
- Molar specific heats of an ideal gas
- Molar Specific Heat at Constant Volume
- Molar Specific Heat at Constant Pressure
- Definition of Thermodynamics and Work Done in Thermodynamics
- State and Explain First Law of Thermodynamics
- Application of First Law of Thermodynamics
- Definition of Isobaric Process
- Definition of Isochoric Process
- Definition of Isothermal Process
- Definition of Adiabatic Process
- Relation between Specific Heat at Constant Pressure and Specific Heat
at Constant Volume
- Definition of Heat Engine and Essentials of Heat Engine and Heat flow Diagram of Heat Engine.
- Definition of Refrigerator and Essential of Refrigerator and Heat flow Diagram of Refrigerator
- Explain The Second Law of Thermodynamics
- Equivalency of Kelvin and Clausius Statements
- Define and Explain Carnot Engine
- Define and Explain Entropy
- A Carnot engine whose low temperature reservoir is 200K has efficiency 50%. It is
desired to increase this to 75% by how many degrees must the temperature of low
reservoir be decreased if the temperature of high temperature reservoir remains
constant.
- A 200g piece of metal is heated at 150oC and then drop into an aluminum calorimeter of
mass 500g containing 500g water initially at 25oC. Find the final equilibrium
temperature of the system if the specific heat of metal is 128.1 J/kg.K, aluminum is 907
J/kg.K and water is 4200 J/kg.K.
- A heat engine performing 400J work in each cycle has an efficiency of 25%. How much
Heat is absorbed and rejected in each cycle.
- A scientist store 22g gas in tank at pressure 1200 atm overnight the tank develops slight
leakage and the pressure drops to 950 atm calculate the mass of gas escaped.
- In an isobaric process 2000J heat energy is supplied to a gas in a cylinder at constant
pressure of 1.01x105 N/m2
. The piston of area of cross-section 2x102m2 moves through
40cm. Calculates increase in internal energy of system.
- A steel bar is 10m in length is at -2.5oC what will be the change in length when it is
heated to 25oC.
- A Carnot engine performs 2000J of work & rejects 4000J of heat to sink. If temperature
difference between source and sink is 85oC. Find the temperature of source and sink.
- Calculate the density of hydrogen gas, considering it to be ideal gas when root mean
square velocity of hydrogen molecules is 1850m/s at 0oC and at 1 atm pressure.
- Heat engine perform work at rate of 500KW. The efficiency of the engine is 30%.
Calculate loss of heat per hour.
- Find the change in volume of brass sphere 0.6m diameter. When it is heated from 30 oC
to 100oC. ( = 19x10-6 K
-1
)
- A Celsius thermometer in laboratory reads the surrounding is 30oC. What is the
temperature in Fahrenheit & absolute scale?
- The brass ring of 20 cm diameter is to mount on a metal rod of 20.02cm diameter at
20oC. To what temperature should ring be heated. ( = 19x10-6 K
-1
)
- A 100g copper block is heated in boiling water for 10 minutes and then it is dropped into
150g water at 30oC in 200g calorimeter. If the temperature of water is raised to 33.6oC.
Determine specific heat of calorimeter. ( Ccopper = 386J/Kg.K)
- The low temperature reservoir of Carnot engine is at -3
oC and has an efficiency of 40%.
It is desired to increase the efficiency by 50%. By how many degrees should the
temperature of hot reservoir be increased?
- An air storage tank whose volume is 112 L contains 2Kg air at pressure of 15atm. How
much air would have to force to enter tank so that pressure becomes 18 atm. assuming
no change in temperature.
- 1200J of heat energy is supplied to the system at constant pressure. The internal energy
of system increased by 750J and volume by 4.5m3
. Find work done against the piston &
the pressure on the piston.
- Find the root mean square velocity of hydrogen molecule at 100oC take the mass of
hydrogen molecule 3.32x10-
27 Kg. and K = 1.38x10-23J/K.
- A Carnot engine performs 1000J of work & rejects 4000J of heat to sink. If temperature
difference between source and sink is 75oC. Find the efficiency & the temperature of
source.
- A cylinder of diameter 1.00cm at 30oC is to be slid into hole in a steel plate. The hole has
a diameter 0.99970cm at 30oC. To what temperature must the plate be heated?
- If 1 mole of monatomic gas is heated at constant pressure from -30oC to 20oC. Find the
change in internal energy and the work done during the process.
(Cv = 12.5J/K.mol & Cp = 20.8 J/K.mol)
- An ideal heat engine operates in a cycle between temperature 227oC and 127oC. it
absorbs 600 joules of heat find work done per cycle and efficiency
- Find the volume occupied by gram mole of a gas at 10 oC and 1 atm pressure.
- A glass is filled to mark 60 cm3with Hg at 20oC. If flask contents are heated to 40oC how
much Hg will above the mark. (glass = 9x10-6
/K
βHg = 182x103
/K)
- 540 cal of heat is required to vaporize water at 100oC. Determine the entropy change
involved to vaporized 5g water (1cal = 4.2J)
25. The meter bar of steel is measured at 0oC & -2.5oC. what will be difference in their
length at 30oC ( = 11x10-5 K
-1
).