1. Physics 1A, Section 6
November 6, 2008

2. Section Business Quiz 2 grades: Homework #6: Replace FP5 with QP23
mean = 16.1 / 20
median = 16.5 / 20
Homework #6: Replace FP5 with QP23
Quiz 3 will cover:
reading through T.M.U. chapter 11
lectures/sections through today (Nov. 6)
New material includes:
conservation of momentum and energy
non-inertial frames

3. Reading/Lecture Review
T.M.U. chapters lectures:
potential energy U and kinetic energy K
translational kinetic energy: K = ½ mv2
uniform gravity: U = mgh
Newtonian gravity: U = -GmM/r
spring: U = ½ kd2
nonconservative forces: friction, air resistance
Fx = -dU/dx; stable and unstable equilibrium
work: W = energy input = ∫F•ds
power = dW/dt = F•v
momentum p = mv
center of mass: rcm = S miri / S mi
systems of particles
impulsive forces and collision problems

4. Crash Course in Collision Problems
Assume collision happens in an instant.
Describe “before” and “after” cases, nearly simultaneous.
During collision, ignore relatively weak external forces, compared to strong impulsive forces.
Momentum is conserved:
mjvj = constant
Kinetic energy:
elastic:  1/2 mjvj2 = constant
(partially) inelastic:  1/2 mjvj2 decreases
completely inelastic: objects stick to each other

5. Quiz Problem 38

6. Quiz Problem 38 Answer: v0 = sqrt[2g(h-2a)]
before ball collision: M upward, m downward
v1 = v0 (3M-m)/(M+m) = 2v0
height = 4h – 3a

7. Monday, November 10: Final Problem 19 (collision + oscillatory motion)
Quiz Problem 53 (oscillatory motion)
Optional, but helpful, to look at these in advance.

8. Section Business Quiz 2 grades: Homework #6: Replace FP5 with QP23
mean = 16.1 / 20
median = 16.5 / 20
Homework #6: Replace FP5 with QP23
Quiz 3 will cover:
reading through T.M.U. chapter 11
lectures/sections through today (Nov. 6)
New material includes:
conservation of momentum and energy
non-inertial frames