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Chapter 1: Temperature-2 (in Hindi)
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In this lesson discuss the Temperature for Railway ALP CBT2 exam.

Vishal Garg
Mechanical Engineer | Unacademy Plus Educator | Railway Category Expert | Follow me to learn Reasoning |

U
Unacademy user
om Prakash ravat 3members body
yes right
Manju Mj
a year ago
nimm profile nalli personal message edi sir please I HV to ask so many doubts please
  1. Vishal Garg (B.Tech ME Er.) Star and Verified Educator unacademy SSC and Railway Category Expert


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  3. Basic Science & for Railway ALP CBT2 Temperature INDIA Engineering RRB ALP & Technicians Recruitment 2018


  4. TEMPERATURE Temperature is defined as the degree of hotness or coldness ofa bodv. Hot and cold are relative terms. According to kinetic theory of gases, temperature is a measure of average translational kinetic energy ofa molecule i.e., Tk oc (KH) molecules. It is a scalar quantity. Its S.I. unit is kelvin (K) with dimensions Measurement of Temperature A branch of science which deals with the measurement of temperature of a substance is called thermometry. Thermometei is a device used to measure the temperature. Thermometer used for measuring very high temperatures are called pyrometer.


  5. Relationship Between Different Scales of Temperature: C-0 F-32 K-273.16 100212-32 373.16-273.16 R-0 Ra -460 80-0 672-460 To(K) (tC +273.16) Normal temperature of human body is 310.15 k (37 C 98.6 F) STP or NTP implies 273.15 K(0 C-32 F)


  6. Ideal-Gas Equation and Absolute Temperature The equation, where, n - number of moles in the sample of gas. R = universal gas constant; (its value is 8.31 J mol-1 K-1), is known as ideal-gas equation It is the combination of following three laws (i) Boyle's law : When temperature is held constant, the pressure is inversely proportional to volume. i.e., P oc-( at constant temperature) (ii) Charle's law : When the pressure is held constant, the volume ofthe gas is directly porportional to the absolute temperature. i.e., V oc T (at constant pressure) (iii) Avogadro's law : When the pressure and temperature are kept constant, the volume is directly proportional to the nunber of moles of the ideal gas in the container. i.e., V oc n (at constant pressure and temperature)


  7. Absolute Temperature The lowest temperature of-273.16 C at which a gas is supposed to have zero volume and zero pressure and at which entire molecular motion stops is called absolute zero temperature. A new scale of temperature starting with -273.16 C by Lord Kelvin as zero. This is called Kelvin scale or absolute scale of temperature. T(K) toC+273.16 Thermal Expansion The increase in the dimensions of a body due to the increase in its temperature is called thermal expansion. The thermal expansion of solid is classified as follows:


  8. Thermal Expansion The increase in the dimensions of a body due to the increase in its temperature is called thermal expansion. The thermal expansion of solid is classified as follows: 1. Linear Expansion On increasing the temperature of a solid, its length increases. This increase in length of a solid on heating is called linear expansion. The fractional increase in length per C rise in temperature is called coefficient of linear expansion


  9. 1. Linear Expansion On increasing the temperature of a solid, its length increases. This increase in length of a solid on heating is called linear expansion The fractional increase in length per C rise in temperature is called coefficient oflinear expansion. de coefficient of linear expansion, If is coefficient of linear expansion at t1oC then, 21 - length of the rod at t C 22 - length of the rod at t2 C 11 11 [1 + (t2-ti) then,


  10. 2. Superficial Expansion In increasing the temperature of a solid, its area increases. This increase in area is referred as superficial expansion. If the area of solid at temperature t C is A and on heating the rod, the area becomes A2 at t2 C then, where is called coefficient of superficial expansion at t loc Coefficient ofsuperficial expansion is defined as the fractional increase in area per "C rise in temperature. / AT dA A.dT i.e., Coefficient of areal expansion


  11. Applications of Thermal Expansion in Solids (i) Bimetallic strip: If two strips of different metals are welded together to form a bimetallic strip, when heated uniformly it bends in the form ofan arc, the metal with greater coefficient of linear expansion lies on convex side. 0 At tc