PH 212

To make sense out of all of this material, it helps to tie all of the pieces together into one image. This conceptual image is like a rolling landscape. One way of dealing with a lot of interconnected material is to try to find your way through it by following a path, and then back up and starting over if you don't find your answer.

 

A better way to navigate the landscape is by getting a birds-eye view of it, and choose your path with a good idea of where you want to start and end up.

 

To get a birds-eye view of physics entails gaining a conceptual understanding of each problem along the way. The concepts build and mesh together to form a coherent landscape.

 

The material we have studied falls into these main categories:

 

• Motion in a plane
• Gravity
• Rotation
• Waves
• Ray optics

 

The categories can be broken down further into related topics

 

• Motion in a plane
  • dynamics of circular motion
    • kinematics
    • uniform and nonuniform circular motion
  • circular orbits
  • fictitious forces - centrifugal force
• Gravity
  • Newton's law
  • gravitational force
  • Kepler's laws
  • gravitational energy
  • orbits
• Rotation
  • rolling
  • moment of inertia
    • center of mass
  • torque
    • static equilibrium
  • angular momentum
• Waves
  • oscillations
    • simple harmonic oscillations
      • springs
      • pendulums
        • simple
        • physical
  • traveling waves
    • sound waves

• • • standing waves
      • harmonics
  • light waves
  • power, intensity, decibels
  • Doppler shift
• superposition
  • constructive and destructive interference
  • beats
• wave optics
  • single slit, double slit, diffraction gratings

• Ray optics
  • reflection
  • refraction
    • index of refraction
    • Snell's law
    • lenses
      • converging and diverging
        • ray diagrams
        • thin lens formula
        • magnification

 

This sounds like a lot of topics and starts to feel overwhelming. Here's where you want to get a feel for the lay of the land. For the various topics, what kinds of frameworks are helpful?

 

• kinematics
• sum of forces
  • linear motion
  • circular motion
• conservation
  • energy
  • angular momentum
• geometry
• moments

 

A good test question often utilizes two or more approaches in finding the solution. Break down the problem into concepts and think about what approach to use for each conceptual part.

 

If you find yourself going down a path for the answer without regard to the landscape, often you will get an answer, but it is not in terms of given variables.

 

This means that you need another equation. Often, you need to consider another approach.

 

Solving physics problems is a layered process. Frameworks are layered into the landscape, along with conceptual areas.

 

If you are having trouble understanding what to to, draw a picture. Often, more than one picture or diagram is needed to fully understand how to proceed.

 

 

• Think about the physical situation
• identify given variables
• identify the variable you need to solve for
• draw a diagram (at least one)
• connect the diagram to events in space or time
• think about what frameworks apply to the problem at hand
• apply the mathematical formula to your diagram(s)
• work the math
  • solve completely algebraically
• check your solution
  • it is in terms of given variables?
    • if not, find another appropriate framework
    • may need another diagram
    • identify the formula you need and proceed
  • do the units check?
  • is the answer reasonable?

 

If you apply this method that you have been practicing in your daily work, it will help you to analyze a test question, even if you have not seen exactly that question before.