Physics 121P, Spring 2014
Unit 7
Unit 7 Work and Energy (chapter 7, Fundamentals of Physics 10th edition)
Introduction
The previous units have led up to an understanding of Newtons Laws of motion,
which contain all of the information needed to predict the
Physics 121P, Spring 2014
Unit 1
Unit 1 Measurement, Numbers, and Physical Units
Introduction
Chapter 1 - Fundamentals of Physics (10th edition).
As a physicist, one tries to make observations of the surrounding universe which can be
expressed as numbers.
Lecture 15. Rolling
Rolling
Energy conservation in rolling
Vector form of torque
Review of Chaps. 7-10
1
Summary of Previous Lecture
Kinematic Equations
(t ) 0 t
1
(t ) 0 0t t 2
2
Linear and
AngularRelated
s r ,and
v
r
Linear
angular
related by r
at r
Lecture 7. Application of
Newtons Laws
Newtons third law
Application of Newtons laws
Friction
1
Summary of Previous Lecture
Newtonian Mechanics
Forces are pushes or pulls
Forces cause acceleration
Mass
Newton's First Law
If there is no net force on a
b
About Midterm 2 on 3/17
Assignment 7 due at 9:00pm, Wednesday, March
16. The solutions posted at the same time, and no
late homework.
The exam will be held from 9:40 to 10:55am on
Thursday, March 17 in Hoyt Hall.
Chapters 7-10 will be covered.
Closed-
About Midterm 3 on 4/12
Assignment 10 due at 9:00pm, Monday, April 11.
The solutions posted at the same time, and no late
homework.
The exam will be held from 9:40 to 10:55am on
Tuesday, April 12 in Hoyt Hall.
Chapters 11-14 will be covered.
Closed-bo
Lecture 6. Newtons Law
Force and mass
Newtons 1st law
Newtons 2nd law
Common forces
1
Summary of Previous Lecture
Projectile Motion
Flight of particle subject
only to free-fall
acceleration (g)
Uniform Circular Motion
Magnitude of
acceleration:
Time to co
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PHY 122 HW 1 Solutions
2
1. We have seen that Coulombs Law (k Qr1 Q
, k = 9 109
2
m2
2
Gravitation (G Mr1 M
, G = 6.67 1011 Nkg
2
2 ).
N m2
C2 )
appears to be very similar to Newtons Law of
(a) Approximately how many times larger is k than G?
(b) Take 2 e
PHY 122 HW 2 Solutions
1. For a spherical surface centered around a point charge, the formula for electric flux E = E dA simplifies to
E = EA. Why? If our spherical surface is surrounding an electric dipole rather than a point charge, this simplification
PHY 122 HW 5
1. A square parallel plate capacitor has sides with a length of 1cm and a separation
between the plates of 1 m. If we fill the capacitor with a dielectric in order to
achieve a capacitance of 0.1 F, what does the dielectric constant need to b
PHY 122 HW 12
1. For the circuit below, draw phasors for I1 , I2 with Vab . Hint: start with Vab and I1 . Write an expression relating I1 and
I2 .
2. You are being held hostage on a jungle island by guerillas, not gorillas (bonus points if you know what m
PHY 122 HW 4 Solutions
1. If we multiply 1 Coulomb by 1 Volt, what type of quantity are we left with (i.e.
force, power, distance, etc)? How does this quantity relate to an electron volt?
Concepts
Units
Electric Potential
Electric Potential Energy
Ta
PHY 122 HW 2
1. For a spherical surface centered around a point charge, the formula for electric flux E = E dA simplifies to
E = EA. Why? If our spherical surface is surrounding an electric dipole rather than a point charge, this simplification
does not w
PHY 122 HW 7
~ which is perpendicular to the particles velocity, ~v . Will its
1. An electron enters a region of uniform magnetic field, B,
kinetic energy increase, decrease, or stay the same? Explain.
Solution: Since the particle is in circular motion,
PHY 122 HW 6 Solutions
1. Explain the difference between EMF and terminal voltage in an ideal battery.
Give an example where the difference between the two might matter.
Solution: The EMF () is the potential difference between the terminals
when no curre
Lecture 20. Fluid Motion
Archimedes Principle
Continuity
Bernoullis Equation
1
Summary of Previous Lecture
Energy in Planetary
Motion
GMm
GMm
U
U
,
K
r
2r
2
Fluid Pressure
A substance that can flow
Can exert a force
perpendicular to its surface
Escape
Lecture 21. Oscilation
Oscillation
Simple harmonic oscillation
Pendulum
Review on Chaps. 11-14
1
Summary of Previous Lecture
Pascal's Principle
A change in pressure applied to
an enclosed incompressible
fluid is transmitted
undiminished to every portion o
Lecture 5. Motion in 3D
Projectile motion
Uniform circular motion
Relative motion
1
Summary of Previous Lecture
Scalar Product
Dot product
Cross Product
Produces a new vector in
perpendicular direction
Direction determined by righthand rule
Position Ve
Lecture 22. Waves
Damped oscillation
Forced oscillation and
resonance
Wave properties
1
Summary of Previous Lecture
Frequency
1 Hz = 1 cycle per
second
Period
The Linear Oscillator
Simple Harmonic
Motion
Find v and a by differentiation
Energy of SHO
1
Lecture 3. Vectors
Scalar and vector
Vector sum by geometry
Components and unit vector
Vector sum by components
Scalar times vector
1
Summary of Previous Lecture
Position
Relative to origin
Positive and negative
directions
Displacement
Change in position
Lecture 9. Work
Kinetic energy
Work
Work by gravitational force
Hooks law
1
Summary of Previous Lecture
Drag Force
Resistance between a fluid and
an object
Opposes relative motion
Drag coefficient C
experimentally determined
Use the effective crosssection
Lecture 12. Center of Mass
Center of mass
Motion of particle system
Momentum
Conservation of momentum
1
Summary of Previous Lecture
Potential Energy Curves
Power
At turning points a particle
reverses direction
At equilibrium, slope of U(x)
is 0
Work Done
Lecture 13. Collision
Elastic and inelastic collision
Collision in 2D
Rocket
Rotation
1
Summary of Previous Lecture
Center of Mass
Special point an object
treated as a particle
1
r
rcom
M
r
mi ri
n
M mi
i 1
Motion of Center of
Mass
Newton's 2nd Law
i 1
Lecture 10. Potential energy
Work by general force
Power
Potential energy
Conservation of Mechanical
Energy
1
Summary of Previous Lecture
Kinetic Energy
The energy associated with
motion
Work
Energy transferred to or from an
object via a force
Can be posi
Lecture 17. Equilibrium
Static Equilibrium
Elasticity
Stress and strain
1
Summary of Previous Lecture
Angular Momentum of
a Particle
Angular Momentum of a
Rigid Body
Newton's Second Law
in Angular Form
Conservation of Angular
Momentum
Precession of a G
About Final Exam on 5/5
The exam will be held from 7:15 to 10:15pm on
Thursday, May 5 in Hoyt Hall.
Chapters 1-17 will be covered.
Closed-book exam. Allowed 1 page (8.5x11 in.) of
summary sheet and a scientific calculator.
There will be 10 problems. T
Lecture 18. Gravitation
Newtons law of gravitation
Gravitational potential
Keplers laws
1
Summary of Previous Lecture
Static Equilibrium
Tension and
Compression
E is Young's modulus
Center of Gravity
If the gravitational
acceleration is the same
for al
Lecture 24. Beat and Heat
Sound intensity
Doppler effect
Thermal expansion
Heat capacity
1
Summary of Previous Lecture
Interference of Waves
Sound Waves
Two sinusoidal waves on
the same string exhibit
interference
Speed of sound waves in
a medium having b
About Midterm 1 on 2/16
Assignment 4 Due at 9:00pm, Monday, Feb. 15.
The solutions of Assignment 4 will be posted at the
same time, and no late homework will be accepted.
The exam will be held from 9:40 to 10:55am on
Tuesday, Feb. 16 in Hoyt Hall.
Chap
Lecture 4. 3D Kinematics
Scalar product
Vector product
Motion in higher dimension
1
Summary of Previous Lecture
Scalars and Vectors
Scalars have magnitude only
Vectors have magnitude and
direction
Both have units!
Vector Components
Given by
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