1. Homework Work Mastering Physics Assignments Study for Exam
rotational motion
torque and angular momentum
static equilibrium
gravity
Review Session - 7 PM - HL 188
Work Reading Assignment for Friday
Work on Lab Presentation

2. Example
A 150 kg satellite is in circular orbit of radius 7.3 Mm about the earth.
Determine the potential energy.
U = -8.2 x109 J
Determine the orbital speed.
v = 7400 m/s
Determine the kinetic energy.
K = 4.1x109 J
What is the escape speed from this altitude?

3. Exercise
Why are rocket launch sites located nearer to the equator (rather than the poles)?

4. Angular Momentum in the Bohr Model of the Atom
The electron orbits like a planet.
The electron can only have certain values of angular momentum.
L = n (h/2) where n is an integer

5. Angular Momentum in Quantum Mechanics
L =  (h/2)
gives length of angular momentum vector
Lz = ml (h/2)
gives orientation of the angular momentum vector
The Bohr quantum number Lz L 

6. Quantum Numbers determine the shape of the state
l = for s-state
l = for p-state
l = for d-state
L = r x mv
Only s-states (L = 0) can have electrons at the origin.

7. More Static Equlibrium
How does a truck scale work?
If the front wheels give a weight of N, the middle wheels (which are 3 m back) give a weight of N and the rear wheels (which are 10 m further back) give a weight of N, where is the center of mass of the truck?

8. Opening the paint can
A man tries to pry the lid off a can of paint with a very light screwdriver.
A force F is applied a distance L from the edge of the can. The screwdriver pushes up on the lid a distance d from edge of the can.
What is the upward force on the lid?
What is the normal force supplied by edge of the can on the screwdriver?

9. Example
If the wall is frictionless, the floor is not, what are the forces acting on the ladder?

10. Followup
If the wall is frictionless, the coefficient of static friction between the ladder and the floor is 0.8, how large is the force of static friction?

11. Example
At what angle will the contents spill?

12. Example
A 9 m flagpole hangs in a horizontal position from the side of a building. It is supported by a hinge and a 15 m cable. Find the tension in the cable and the magnitude and direction of the force supplied by the hinge if the flagpole weighs 1500 N?