PHYS 172: Modern Mechanics
Spring 2017
Lecture 01
Tuesday, Jan. 10th
INTRODUCTION
Instructors: Prof. Andrew Hirsch, Prof. Mark Haugan
(Course Coordinator), Prof. Oana Malis, Dr. Carina
Rebello
Email: [email protected], [email protected][email protected],
Nina Roslan
PHY221
Experiment E7
Conceptual Question
a) Increase the power of lens
When power of lens is increases, the focal length decreases because
power is inversely proportional to focal length
b) Gauss formula
Decreasing the radius of converging len
Nina Roslan
Experiment E4
Conceptual question
1. The brightness of bulb A and B will be not as bright as they have to share the
current in the circuit but they will have the same brightness.
2. The brightness of bulb A and B is very bright but they will h
Nina Roslan
Conceptual Question
Experiment E6
PHY221
1)

Since the magnets start point is very far away the initial flux will
bezero, because the magnetic field lines will not be passing
through the coil at all.

Since the magnets end point very far awa
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Physics 209
Fall 2013
Thermal Physics Class #14
Thermal Averages and the Equipartition Theorem
Friday, October 4, 2013
I. Thermal Averages
A. Expectation Value: The expectation value of a quantity A is given by
X
hAi =
(Probability of A) A.
poss. values o
Example Problem 1. The emissivity of tungsten is 0.35. A tungsten sphere with radius 1.50 cm is
suspended Within a large evacuated enclosure Whose walls are at 290 K. Find the electrical power input that
is required to maintain the sphere at temperature o
Example Problem 1. Example Heat Engine.
When thinking about heat engines, it is often useful to have a specic example in mind. Below is a silly,
but simple example of a heat engine which operates in a cycle that is used to lift sand to a platform. The
ass
Example Problem 1. A 1.0 kg ice block at 0C slowly melts in a room that is very slightly warmer than
the ice cube. Find the change in entropy of the ice cube.
A. Model. Is the process reversible? If not, what reversible process will you use to calculate t
Example Problem 1. You are asked to design the most efcient possible heat engine that can lift a 15 kg
mass 2.0 In each cycle While using 500 J of heat input from a high temperature reservoir that is at 500C. (a)
What type of cycle will you use? Sketch th
Entropy Changes in Macroscopic
Processes
Thermal Physics Class 16, Monday, October 1, 2012
NO Journal Club Monday
Chris Ramsey
Washington University Dual Degree Program
Tuesday, October 8th
12:10 p.m., Goodrich 104
Entropy of Ideal Monatomic Gas
By calcul
Phys 209 Homework #17
Due: Fri, Oct. 11
Name:
Problem 1. (20 points) A heat engine takes 0.350 moles of air around a cycle as follows:
1 2: The air initially at 300 K and 1.00 atm is heated isochorically until the temperature
doubles to 600 K.
2 3: Then t
Example Problem 1. Estimate the rms speed of an air molecule in a room at normal room temperature.
A. Model.
B. Visualize/Parameterize.
C. Math. [Formula First]
ID. Assess.
Solution.
A A$UVK +l 'lk/ \ptatl gas Racy/l 3x5 val)l
ma M, New ,2; Maj In, 6:490t
Physics 209
Spring 2013
Thermal Physics Class #3
Heat Conduction
Friday, September 6, 2013
I. Heat Conduction: Heat flow via direct thermal contact between bodies at different temperatures.
The rate of heat flow through a material of crosssectional area
#WD!
goloJmom W
Name:
Problem 1. (10 points) Some 3.0 X 1022 molecules of nitrogen gas at 280 K are in a chamber with a piston
that expands isothermally to 3 times its original volume. (a) Sketch a PVdiagram of this process. (b)
Explain Why heat must en
HW 12 
Name:
Problem 1. Consider two Einstein solids A (contains 1 atom) and B (contains 2 atoms) which have a
combined energy U A + U13 = 65. These systems, which are isolated from their surroundings, are placed
into thermal contact. (a) Without using
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Problem 1. (10 points) Imagine that a quantum system has exactly three energy states, with energies 0.020
eV, 0.040 eV, and 0.060 eV, respectively. At room temperature, out of every 1000 of these systems, about
how many are in each state?
Name:
Phys 209 TPHW#05
Due: Wed., Sep. 11
Problem 1. (10 points) The rate at which radiant energy from the sun reaches the earths upper atmosphere
is about 1370 W/m2 . The distance from the earth to the sun is 1.50 1011 m, and the radius of the sun is
6.
Physics 209
Spring 2013
Thermal Physics Class #0
Thermal Energy
Friday, August 30, 2013
I. Definitions
A. Heat (Q): The energy that flows across the boundary between two objects as a result of a
difference in temperature between them.
B. Work (W ): The en
TPHW16
g 0 ii) l )O M S =
Problem 1. (10 points) (a) Imagine that the temperature of a 220g block of aluminum sitting in the sun
increases from 18C to 26C. By how much has its entropy increased? (b) A puddle containing 0.80 kg of
water at 0C freezes on a
Physics 209
Fall 2013
Thermal Physics Class #8
Thermodynamic Processes
Wednesday, September 18, 2013
I. Thermodynamic Processes
A. Quasistatic Process: A process that occurs at rate much slower than the typical relaxation
times of the system so that it al