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