Physics 1600 Exam Preparation

End Term

• It seems like I need to do some self-study, such as reviewing topics related to 7.5.

Office Hour

• Things I want to ask:
  • Newton’s laws do not work when mass changes.
  • Kinetic energy during Galilean transformation.

Practice Final

• Pay attention to the limit of integrating logarithms.
• Understand how harmonic motion can be obtained using F=-dU/dx and Taylor expansion.
• Note that dm/dt is a rate, while Δm is not.
• Even if it says “momentum of inertia,” it may be negligible.

Pset 10

• q2: It is important to understand why both frames are internal frames when velocity is constant.

  • There is an external force, but since it is a Galilean transformation in the ground frame, there is no problem.
  • In this case, the change in ΔK depends on the change in distance and work done, so the root cause is that an external force arises in the car frame.
  • Also, why is d an inertial frame?
  • In this case, there is no external force, so considering the center of mass makes it an inertial frame.
  • In this case, the change in ΔK is the same regardless of the frame, so it makes sense.

• q3: When p=p0, it is important to note that the mass dividing expression can be replaced with an area dividing expression.

  • Since p0 is in both the numerator and denominator of the integral, it can be taken out as a constant and canceled.
  • Forgetting this could lead to confusion during the exam.

• q4: This is a very educational problem.

  • Case 1:
    • Here, we only consider acceleration without considering force.
    • Force can be imagined as acting in various directions to match the acceleration.
    • In this case, the velocity change = acceleration only has an r hat direction.
    • Therefore, angular momentum can be considered conserved, which is equivalent to angular velocity being conserved.
  • Case 2:
    • No, I still don’t understand.
    • Only radial acceleration = only radial force = 0 torque = radial momentum conserved is incorrect.
    • The acceleration in polar coordinates is complicated.

Midterm 2

• Gravitational acceleration: $\frac{-GMm}{m{r}^2}=\frac{-GM}{r^2}$
  • The mass cancels out, so it does not depend on mass.
• Electrostatic acceleration: $\frac{-GQq}{m{r}^2}$
  • The mass does not cancel out, so it depends on both mass and charge.

Pset 6

• There are many good problems, so I should seek revenge.
  • q4: In polar coordinates, the r projection of acceleration and r dot dot do not match.
  • q5: The dot Θ does not become speed.
  • These are dangerous.

Pset 7

• Insight: If the velocity and the direction of the vector are different, it will not be added to the energy.
• I want to understand this intuitively.

Pset 8

• ω = v/R
• I want to understand this relationship correctly. It’s W=ΔK, not W=K.

To-Do

• Read the lecture notes.
• Solve the mock exam.
• Memorize polar acceleration.
• Remember √g/l, etc.
• Think about the part on line integrals that I don’t understand.
• Why does force conserve even if it’s not F(x)?

Midterm 1

To-Do

• Review the Physics 1600 Review Plan and aim to understand various equation transformations and their results so that I can explain them without looking at anything.
• Things I want to be able to explain on my own:
  • Positive and negative aspects of Simple Harmonic Motion.
  • Derivation of velocity and acceleration in Cartesian and polar coordinates.
• Solve past exams.
• Review past problem sets.
• October 12th:
  • -1100 Study Polar Coordinates.
  • -1200 Review other topics.
  • Do laundry.
  • Review problem sets and solve them again if necessary.
• If there is time:
  • Read the discussion on 4.1.6.
• A tip I realized:
  • It’s obvious, but it’s important to visualize graphs and check dimensions.
  • It helps me catch mistakes.