Question

The principle of conservation of heat energy states that
that when an object is at constant temperature or is in thermal equilibrium, it is losing and gaining heat at equal rates.
the heat lost by a hot body is equal to the heat gained by the cold body in any system provided there is no heat exchange between the substances involved and their surrounding
It is defined as the process in which molecules move from area of high concentration to another area of low concentration until an equilibrium concentration is established within the system under consideration
(P+aV2)(V−b)=RT

Answer 1

@paki

Answer 2

@paki

Answer 3

@paki

Answer 4

@paki

Answer 5

@Michele_Laino

Answer 6

you are referring to the chemical potential

Answer 7

ok.

Answer 8

so, which of the option is right?

Answer 9

using statistical physics, we can show that particles tend to move from a region of higher chemical potential, to a region of lower chemical potential, as the system approaches equilibrium

Answer 10

ok

Answer 11

so at equilibrium, the chemical potential has to be equal for all subsystems of the original system
Furthermore, an equilibrium state, is characterized by a definite value of Temperature, Pressure and Volume, since it has to be represented on a plane P-V for example

Answer 12

so, option d

Answer 13

I think b.

Answer 14

ok.

Answer 15

Hooke’s law states that

Answer 16

the force applied on elastic material is directly proportional to the acceleration produced provided the elastic limit is not exceeded.
the force applied on elastic material is directly proportional to the extension produced provided the elastic limit is exceeded.
the escape thrust applied on elastic material is directly proportional to the extension produced provided the elastic limit is not exceeded.
the force applied on elastic material is directly proportional to the extension produced provided the elastic limit is not exceeded

Answer 17

please wait a moment

Answer 18

ok waiting

Answer 19

here the equation of a spring is:
\[F = - kx\]
where k is the constant spring
and x is the elongation of the spring

Answer 20

ok. D then

Answer 21

yes!

Answer 22

The latent heat of fusion of pure water is
334kJ/kg
. How much energy would it take to melt 3 kg of ice at
0oC
to water at
0oC
111 kJ
334 kJ
668 kJ
1 000 kJ

Answer 23

it is very simple, by definition of latent heat, the requested amount of heat is:
Q=334 * 3=...?

Answer 24

1002

Answer 25

yes!

Answer 26

so what is the right option?

Answer 27

1000

Answer 28

ok!

Answer 29

or 668?

Answer 30

no, I don't think, since the formula, is:
\[Q = \lambda \times m\]
where \lambda is the latent heat = 79.7 kCal, and m is the mass of water

Answer 31

ok. please continue

Answer 32

now we can write:
79.7 kCal = 79.7*4184 =333.5 kJoules
so:
Q= 333.5 * 3=1000.5 kJoules

Answer 33

waw. u must be a genus

Answer 34

thanks!

Answer 35

The absolute zero temperature refers to the temperature at which
pure ice, water and water vapour at normal atmospheric pressure are in equilibrium
theoretically all thermal motions will cease
pure ice melts at normal atmospheric pressure
pure ice ecomes steam at atmospheric pressure

Answer 36

sorry the unit of measure of latent heat is kJoules/Kg, or kCal/Kg

Answer 37

when T=0 K all molecules and atoms and quarks are theoretically at rest.
We say theoretically, because we can not have a particle at rest since it is against the Heisenberg Principle

Answer 38

so A?

Answer 39

no, A. it is not, since that is the definition of the triple point of water

Answer 40

so what about B. it must be B right

Answer 41

yes!

Answer 42

Two bodies may be said to be in thermal equilibrium if
the bodies are thermally insulated from one another
the bodies are not in thermal equlibrium with another body
if one body loses heat to the other
if there not net flow of heat between the two bodies two bodies in thermal contact

Answer 43

i think D

Answer 44

yes! I think so!

Answer 45

Thermal expansion of a solid material depends on the following EXCEPT
the nature of the material making up the solid
the range of the temperature change
the initial dimensions of the solid
average translational motion of constituent atoms of the material

Answer 46

for example, the thermal expantion of a rod with initial length L0, and thermal dilation coefficient \lambda, is:

\[L = {L_0}(1 + \lambda \times \Delta t)\]
where L is the final length, and Delta t is the change of temperature.
Of course \lambda depends on the material

Answer 47

oops..expansion*

Answer 48

so what is the option? D?

Answer 49

D?

Answer 50

or C?

Answer 51

I think D

Answer 52

Tensile strain is mathematically expressed as:
Force/Area
initial length/extension
extension/initial lenght
Stress + initial lenght

Answer 53

since L_0 is the initial length

Answer 54

by definition it is the ratio between a force and an area

Answer 55

thought as much

Answer 56

Which of the following does NOT determine the amount of internal energy an object has?
temperature
amount of material
type of material
shape of the object

Answer 57

D?

Answer 58

yes! of course!

Answer 59

A certain resistance thermometer at triple point of water has resistance of
152.0Ω
. What is the temperature of the system in degrees celcius when the resistance of the thermometer is
230.51Ω

Answer 60

414.2o
C
141.0o
C
253.2o
C
80.4o
C

Answer 61

here we have to apply this formula:
\[\Large R\left( t \right) = {R_0}\left( {1 + \alpha t} \right)\]
where \alpha is the temperatur coefficient, and R_0 is the initial resistance

Answer 62

ok

Answer 63

do you know what is the value of \alpha?

Answer 64

no, please what is the value?

Answer 65

wait a moment, I think that we have to apply another formula

Answer 66

ok

Answer 67

please wait a moment another student asked me to help him

Answer 68

ok. am waiting sir

Answer 69

hello sir, still waiting

Answer 70

@Michele_Laino

Answer 71

sincerely I'm confused, since the formula which models the temperature of a thermometer, is:
R=R_0(1+At+Bt^2)
where R_0, A , B are three coefficients. Nevertheless we have not enough data in order to determine those cefficients

Answer 72

ok. no probs. what about this?

Answer 73

The temperature at which the tungsten filament of a 12 V and 36W lamp operates is
1730o
C. If the temperature coefficient of resistance of tungsten is
6×10−3
/K, find the resistance of the lamp at a room temperature of 20oC
10.00Ω
0.45Ω
0.39Ω
4.00Ω

Answer 74

here we have to apply the formual above, namely:
\[R\left( t \right) = {R_0}\left( {1 + \alpha t} \right)\]
where \alpha is 6×10−3 and t= 20°C. So, what do you get?

Answer 75

R(t)=R(1.12)

Answer 76

and R_0= 1730 ohms
so:
R=1730*1.12=...?

Answer 77

1937.6

Answer 78

so, what next sir?

Answer 79

I got:
0.006*20=0.12

Answer 80

ok.
R=1730*0.12=207.6

Answer 81

what next sir?

Answer 82

oops.. we have:
R=4 ohm at t=1730 °C
now we want to compute the resistance at t=20°C

Answer 83

ok

Answer 84

please give the solution sir

Answer 85

we have to solve this equation:
\[\frac{4}{x} = \frac{{1 + 0.006 \times 1730}}{{1 + 0.006 \times 20}}\]
what is x?

Answer 86

0.046