Hi all,
This is to notify you all that Assignments on topics thermodynamics and gravitation are now available on the OLP page of our website for downloading them along with their solutions visit http://physicscatalyst.com/olp.php
hope it will help you.
Showing posts with label Thermo Study Material. Show all posts
Showing posts with label Thermo Study Material. Show all posts
Sunday, 26 December 2010
Monday, 4 February 2008
Some points to note
1. Isothermal Process
Pv=constant
VdP+PdV=0
-VdP/dV=P
Now Bulk Modulus= -VdP/dV
So Bi=P
Adiabatic Process
PVy=constant
VydP+PyVy-1dV=0
So Ba=yP
2. if A sold sphere and a hollow sphere having same material and size are heated to same temperature and allowed to cool in the same surrounding ,it has been found that hollow sphere cools faster than solid sphere
Pv=constant
VdP+PdV=0
-VdP/dV=P
Now Bulk Modulus= -VdP/dV
So Bi=P
Adiabatic Process
PVy=constant
VydP+PyVy-1dV=0
So Ba=yP
2. if A sold sphere and a hollow sphere having same material and size are heated to same temperature and allowed to cool in the same surrounding ,it has been found that hollow sphere cools faster than solid sphere
Thursday, 31 January 2008
Tuesday, 29 January 2008
Some study tips for Thermodynamics
1. Always make sure you Heat(Q) ,Internal Energy(U) & Work(W) with correct sign in equation
ΔU=Q-W
W is positive when work done by the system(Increase in Volume)
W is negative when work done on the system(Decrease in Volume)
Q is positive when heat is given to the system
Q is negative when heat is taken from the system
2. workdone in a cycle is equal to the area enclosed on the PV diagram
3. Change in Internal energy is zero for a cycle
So Net Heat=Net Work done
4.All Bodies emit radiation at all temperature.Radiation emmited are of diffrent frequencies.Frequency at which most radiation are emmitted are directly proportional to Temperature of the body.
ΔU=Q-W
W is positive when work done by the system(Increase in Volume)
W is negative when work done on the system(Decrease in Volume)
Q is positive when heat is given to the system
Q is negative when heat is taken from the system
2. workdone in a cycle is equal to the area enclosed on the PV diagram
3. Change in Internal energy is zero for a cycle
So Net Heat=Net Work done
4.All Bodies emit radiation at all temperature.Radiation emmited are of diffrent frequencies.Frequency at which most radiation are emmitted are directly proportional to Temperature of the body.
Friday, 18 January 2008
Thermal Expansion
- Increase in dimension of body due to increase in temperature is call thermal expansion
- Most of the solid material expand when heated
-Consider a rod of length L then for small change in temperature ΔT,the fractional change in length ΔL/L is directly propertional to ΔT
ΔL/L=αΔT --(2)
or ΔL=αLΔT --(3)
- constant α characterizes the thermal expansion properties of a particulaqr material and it is known as coefficient of linear expansion.
- for materials having no prefential direction,every linear dimension changes according to equation (3) and L could equally well represent the thickness of the rod,side lenght of the square sheet etc
-Normally metals expand more and have high value of α
- Agian consider the intial surface area A of any surface .Now when the temperature of the body is increases by ΔT ,the increase in surface area is given by
ΔA=αAAΔT ----(4)
where αA is the coefficient of area expansion
-Similary we can define coefficient of volume expansion as fractional change in volume ΔV/V of a substance for a temperature change ΔT
as ΔV=αVVΔT ----(5)
- K-1 is the unit of these coefficents expansions
- These three coefficent are not strictly constant for a substance and these value is depends on temperature range in which they are measured.
Relation between volume and linear coefficient of expansion for solid materail: Consider a solid parallopide with dimension L1,L2 and L3
then volume is
V= L1L2L3
when temperature increase by a amount ΔT then each linear dimension changes and then new volume is
V+ΔV=L1L2L3(1+αL )
V+ΔV=V(1+αLΔT)3
V+ΔV=V(1+3αLΔT+3αL2ΔT2+αL3ΔT3)
if ΔT is small the higher order can be neglected.Thus we find
V+ΔV=V(1+3αLΔT)
ΔV=3αLVΔT
Comparing this with equation (5) we find
αV=3αL
- Increase in dimension of body due to increase in temperature is call thermal expansion
- Most of the solid material expand when heated
-Consider a rod of length L then for small change in temperature ΔT,the fractional change in length ΔL/L is directly propertional to ΔT
ΔL/L=αΔT --(2)
or ΔL=αLΔT --(3)
- constant α characterizes the thermal expansion properties of a particulaqr material and it is known as coefficient of linear expansion.
- for materials having no prefential direction,every linear dimension changes according to equation (3) and L could equally well represent the thickness of the rod,side lenght of the square sheet etc
-Normally metals expand more and have high value of α
- Agian consider the intial surface area A of any surface .Now when the temperature of the body is increases by ΔT ,the increase in surface area is given by
ΔA=αAAΔT ----(4)
where αA is the coefficient of area expansion
-Similary we can define coefficient of volume expansion as fractional change in volume ΔV/V of a substance for a temperature change ΔT
as ΔV=αVVΔT ----(5)
- K-1 is the unit of these coefficents expansions
- These three coefficent are not strictly constant for a substance and these value is depends on temperature range in which they are measured.
Relation between volume and linear coefficient of expansion for solid materail: Consider a solid parallopide with dimension L1,L2 and L3
then volume is
V= L1L2L3
when temperature increase by a amount ΔT then each linear dimension changes and then new volume is
V+ΔV=L1L2L3(1+αL )
V+ΔV=V(1+αLΔT)3
V+ΔV=V(1+3αLΔT+3αL2ΔT2+αL3ΔT3)
if ΔT is small the higher order can be neglected.Thus we find
V+ΔV=V(1+3αLΔT)
ΔV=3αLVΔT
Comparing this with equation (5) we find
αV=3αL
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