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Thermodynamics
Thermodynamics
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#physics, #heat, #energy, #thermodynamics
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1
The idea that heat will always flow from objects with higher temp to objects with lower
is derived from the zeroth law of thermodynamics.
is derived from the second law of thermodynamics.
is derived from the first law of thermodynamics.
is derived from the third law of thermodynamics.
2
Which are isothermal? Look at the PV diagram.
1 to 2 and 2 to 3
1 to 2 and 3 to 4
2 to 3 and 3 to 4
2 to 3 and 4 to 1
3
The 1st Law of Thermodynamics states that
the sum of the kinetic and potential energies is constant
bodies at the same temp don't exchange heat.
disorder tends to increase in the universe
internal energy change is the sum of work and heat
4
Which statement is most likely true about the graph below
pink is isothermal; blue is isometirc
pink is isobaric; blue is adiabatic
pink is adiabatic; blue is isothermal
pink is isothermal; blue is adiabatic
5
Over time, the entropy of the universe
is stabilizing
is varying
is decreasing
is increasing
6
Which of the following is a characteristic of an isochoric process?
The internal energy does not change.
The entropy does not change.
The temperature does not change.
No work is done on or by the system.
7
Carnot efficiency:
Is attainable maximum theoretical efficiency.
Carnot imagined a nuclear cylinder moving from hot to cold.
Even under Carnot's ideals, 100% efficiency can't happen.
Real processes involve smooth flows--reversal is possible.
8
Which of the following is NOT true concerning phase changes?
Latent heat of vaporization is greater than for fusion.
Latent heat of fusion is the temp increase as a solid melts.
When a liquid freezes, it releases thermal energy.
When a liquid vaporizes, it absorbs thermal energy.
9
A refrigerator
Makes the Ql bigger.
pumps heat from one area to another.
Overall, refrigerators reduce heat.
operates without work.
10
A system absorbs 1500 J of heat and performs 1500 J of work on its surrounds. The change in Δ U
is -3000 J
is 1500 J
is 3000 J
is 0 J
11
Which of the following is a part of Kinetic Molecular Theory?
Collisions are assumed to be perfectly inelastic.
Molecules do not obey laws of mechanics.
Molecules are far apart--separation distances are vast
A large number of gas molecules moving in random directions
12
How do you describe 3 to 4?
isobaric
expansive
adiabatic
isothermal
13
Pick the correct relationship between k and R. Avogadro's number is N
A
K = RNA
R = kNA
none of these
kR = NA
14
A metal plate has a hole in it. When heated, the hole
gets smaller
gets bigger
changes its shape
stays the same
15
It takes 3730 J of energy to vaporize a quantity of water at STP. What is the entropy change?
37.3 J/K
3.7 J/K
10.0 J/K
13.6 J/K
16
The average KE of the particles. Depends on average speed only.
Heat
Thermal expansion
Temperature
Thermal Energy
17
As objects are heated, the molecules move faster and they expand.
Heat
Thermal Energy
Thermal Expansion
Temperature
18
The pressure on a gas at 27 ° C is tripled as its volume remains constant. The new temp is
9° C
627° C
81° C
300° C
19
What does the area circumscribed by the cycle represent?
Work done ON a Carnot engine.
Heat from a hot Carnot reserve.
Work done BY a Carnot engine.
Wasted generated by a Carnot engine.
20
A completely insulated process is called
isothermal
isometric
adiabatic
isobaric
21
The temperature a gas increases from 100 to 400° K. Which is true about the molecules of gas?
their average speed drops by 1/2
their average speed increases by 2 times
their average speed is unchanged
their average speed increases by 4 times
22
What's happening in a heat engine?
Mechanical energy can be obtained from thermal energy.
Temperatures from from low to high.
A piece of cold wood has high thermal energy that can burn.
There is always a by-product: the hot exhaust of a car.
23
Which of the following represents an increase in entropy?
cleaning your room
ice melting
organizing your physics binder
liquid water freezing
24
An equation representing the 1st Law of Thermodynamics is
ΔU = Q + W
W = -pΔV
ΔU = Q - W
W= pΔV
25
The pressure on 3L of a gas is tripled as its temp stays constant. The new volume is
3 liters
1 liter
9 liters
1/3 liter
26
Which of the following is NOT part of the kinetic theory? Gas molecules
are very far apart except when colliding
undergo elastic collisions with each other
exert attractive forces on each other
have no preferred direction of motion
27
The temperature of a gas increases from 100 to 400 °K. Which is true about the gas molecules?
their average kinetic energy increases by 4 times
their average kinetic energy increases by 2 times
their average kinetic energy is unchanged
their average kinetic energy drops by 1/4
28
Average KE and mass of the particles. Depends on speed and the pass of the particles.
Thermal Energy
Thermal Expansion
Heat
Temperature
29
Where dos the heat flow in? Look at the PV diagram.
2 to 3
1 to 2
3 to 4
4 to 1
30
The 3rd Law of Thermodynamics states
All energy is conserved
Everything can change
We can't get to absolute zero
Energy can only move one direction
31
Transfer of energy between objects that have different temperatures. Hot to cold.
Thermal Expansion
Thermal Energy
Heat
Temperature
