1. PHYS 220 General Physics II
12 FEB 2018
PHYS General Physics II
Today:
Base Groups
Angular momentum
Rolling motion
Oscillations

2. Science Seminar hosted by Natural and Health Sciences
Join us for the first Science Seminar of the
Spring Semester!
Everyone is welcome!
Topic…
Just Think:
Four Lessons from Math
Presenter…
Dr. Andy Rich
Manchester University
Professor of Mathematics
February 12, 2018
Math & Computer Science
4:00 – 5:00 PM
Flory Auditorium (SCIC 203)
Snacks provided

3. Base Group Meeting BGDG: What does your favorite breakfast look like?
Base Group WorkSheet
Group Processing
Reading Quiz

4. Reading Quiz 02 1. The SI unit of charge is the
__A. Ampère __B. Volt __C. Newton __D. Coulomb
2. A proton has the smallest unit of charge, 1.6 x C. All charged objects will have a total charge equal to some multiple of this unit. This is an illustration of
___A. the conservation of charge. ___C. the quantization of charge.
___B. ionization energy. ___D. Coulomb’s law.
3. Like charges repel and unlike charges attract. The force of attraction/repulsion depends on the magnitude of the charges and the distance between them. This is summarized in
___A. the conservation of charge. ___C. the quantization of charge.
___B. the triboelectric effect. ___D. Coulomb’s law.
4. For a damped simple harmonic oscillator which of the following is true?
___ A. Mechanical energy is conserved.
___ B. Mechanical energy is converted into thermal energy.
___ C. Total energy is not conserved.
___ D. Mechanical energy is served, with a light crème sauce.

5. Angular momentum Which, in the absence of external torques,
Where else do we see a cross product?
Units?
kgm2/s
Which, in the absence of external torques,
is a conserved quantity!

6. For a system of particles So that (for constant I )
Angular momentum
For a system of particles
and for rigid bodies
So that (for constant I )

7. Conservation of Angular Momentum
For a system with no external torques, the angular momentum of the system is a constant: If
then

8. EX: Conservation of Angular Momentum
A clay bullet of mass mb and speed vb is fired at a cylinder of
mass M and radius R (initially at rest) with an “impact parameter” b.
Find the angular velocity of the system after the bullet sticks to
the outer surface of the cylinder b
solid cylinder:
I = ½ M R2 R

9. The Work-Energy Theorem
Should look familiar!
Wnet=work done by the net torque

10. Rolling without Slipping
Axle moves at speed vcom
Distance traveled by axle, s, is related to the angle the wheel rotates through by s = R θ,
R = wheel radius
Vcom = ω R (no slipping)
The wheel needs friction to roll!

11. Kinetic energy of rolling
Recall: Vcom = ω R

12. Rolling Motion
Cylinders of different I rolling down an inclined plane:
DK = - DU = Mgh
v = 0
w = 0
K = 0 R M h

13. Join us for the first Science Seminar of the
Seminar day! GO!
Join us for the first Science Seminar of the
Spring Semester!
Everyone is welcome!
Topic…
Just Think:
Four Lessons from Math
Presenter…
Dr. Andy Rich
Manchester University
Professor of Mathematics