1) What is the first step in problem-solving? A) Writing code B) Debugging C) Understanding the problem D) Optimizing the solution Answer: C 2) Which of these is not a step in the problem-solving process? A) Algorithm development B) Problem analysis C) Random guessing D) Testing and debugging Answer: C 3) What is an algorithm? A) A high-level programming language B) A step-by-step procedure to solve a problem C) A flowchart D) A data structure Answer: B 4) Which of these is the simplest data structure for representing a sequence of elements? A) Dictionary B) List C) Set D) Tuple Answer: B 5) What does a flowchart represent? A) Errors in a program B) A graphical representation of an algorithm C) The final solution to a problem D) A set of Python modules Answer: B 6) What is pseudocode? A) Code written in Python B) Fake code written for fun C) An informal high-level description of an algorithm D) A tool for testing code Answer: C 7) Which of the following tools is NOT commonly used in pr...
Heat:
* Temperature is the thermal state of the body, that chooses the direction of flow of heat.
* “Heat is a form of energy transfer between two systems or a system and its surroundings due to temperature difference between them.
Specific heat capacity
* Specific heat capacity of a substance is determined as the quantity of heat required to raise the temperature of 1 kg of the substance through 1K. Its unit is J kg^–1K^–1.
* The specific heat capacity of water is the highest for any substance, 4180 J/kg K. It is 30 times the specific heat capacity
of mercury which is about 140J/kg K.
Specific Latent Heat
Specific Latent Heat of fusion of any substance is the quantity of heat energy needed to melt one kilogram of a substance without change in temperature. The symbol used is L. The unit for specific
latent heat is Joule/kilogram or J/kg
The Gas Laws
* Boyle’s Law
“Temperature remaining constant, the pressure of a given mass of gas is inversely proportional to its volume”.
[Temp remaining constant] It is also be stated as PV = a constant
Charles’ law
* Charles’ Law
States that “Pressure remaining constant, the volume of a given weight of gas is directlyproportional to the absolute
temperature”. This is referred to as the law of volumes. A constant [Pressure remaining constant] It can also be stated as V α T =V/T = a constant
Kelvin Scale or Absolute Temperature:
* The zero of the Kelvin scale corresponds to -273°C and is written as 0K (without the degree symbol). One section on the Kelvin scale has the same magnitude of
temperature as one division of the Celsius or Centigrade scale. Thus 0°C corresponds to +273K.
Kelvin scale(K) = Celsius scale (0°C) + 273
Celsius scale (0°C) = Kelvin scale
(K) – 273
Adiabatic process
In Greek, adiabatic means “nothing passes through”. The process in which pressure, volume and temperature of a system differs in such a manner that during the difference no heat enters or leaves the system is called adiabatic process. Thus in adiabatic process, the total heat of the system remains constant
Carnot engine
* Heat engine is a device which produce mechanical energy from heat energy.
Refrigerator
* A refrigerator is a cooling device. An ideal refrigerator can be regarded as Carnot’s heat engine working in the reverse direction. Therefore, it is also
called a heat pump
Transfer of heat
* There are three ways in which heat energy may get transferred from one place to another place. These are conduction, convection and radiation
Conduction
* By the process of conduction heat is transmitted through the solids
Applications
i. The houses of Eskimos are made up of double walled blocks of ice. Air enfold in between the double walls prevents
transmission of heat from the house to the coldest surroundings.
ii. Birds often swell their feathers in winter to enclose air between their body and the feathers. Air stops the loss of heat from the body of the bird to the cold
surroundings.
iii. Ice is packed in gunny bags or sawdust because, air corned in the saw dust prevents the transfer of heat from the surroundings to the ice. Hence ice does not melt
Convection
* It is a phenomenon of transfer of heat in a fluid with the actual movement of the particles of the fluid
Application
* It plays an major role in ventilation and in heating and cooling system of the houses.
Radiation
* It is the phenomenon of transfer of heat without any material medium. Such a process of heat moves in which no material medium takes part is known as radiation.
Thermal radiation
* The energy emitted by a body in the form of radiation on account of its temperature is called thermal radiation.
It depends on,
(i) Temperature of the body,
(ii) Nature of the radiating body
* The wavelength of thermal radiation ranges from 8 × 10-7m to 4 × 10^-4m. They belong to infra-red region of electromagnetic spectrum.
Properties of thermal radiations
1. Thermal radiations can travel through vacuum.
2. They travel with the speed of light.
3. They can be reflected and refracted. They exhibit the phenomenon of interference and diffraction.
4. They do not heat the intervening medium through which they pass.
5. They obey inverse square law.
Emissive power
* Emissive power of a body at a given temperature is the total amount of energy emitted per unit time per unit area of the surface for a givenwavelength. It is denoted by eλ. Its unit is W m-2.
Perfect black body
* A perfect black body is the one which occupy completely heat radiations of all wavelengths which fall on it and emits heat radiations of all wavelengths when heated. Since a perfect black body neither
transmits nor transmits any radiation, the absorptive power of a perfectly black body is unity.
Kirchoff’s Law
*According to this law, the ratio of emissive power to the absorptive power corresponding to a specific wavelength and at a given temperature is always a constant for all bodies.
(eλ / aλ) = constant = E λ
Stefan’s law
* Stefan’s law states that the amount of heat energy radiated per second per unit area of a perfect black body is directly proportional to the fourth power of its absolute temperature.
(i.e) E α T4 or E = σT4
* Where σ is called the Stefan’s constant. Its value is 5.67 × 10-8 W m-2 K-4.
NEWTON’S LAW OF COOLING
Newton’s law of cooling states that the amount of cooling of a body is directly proportional to the temperature difference between the body and the surroundings
Solar constant
* The solar constant is the amount of
radiant energy received per second per unit area by a perfect black body on the Earth with its surface perpendicular to the direction of radiation from the sun in the
absence of atmosphere. It is denoted by S and its value is 1.388 × 103 W m-2. Surface temperature of the Sun can be calculated from solar constant.
Angstrom Pyrheliometer
* Pyrheliometer is an instrument used to measure the quantity of heat radiation and solar constant.