# Week Six – Becoming Quantitative with Energy

In Class Activity Plan

120 min – Investigating Energy Conservation (Word, Pdf)
PURPOSE: Introduce equations for Eg and Ek, opportunity to design experiment

Teaching Notes:

• You should whiteboard after the first page (making pie charts).

–   Goals here will be to push them towards the answers to the questions on page 2.
–   Suggest energy at the top should be proportional to both mass and height.

• For many students this will be the first time they have ever had to design their own experiment. So this lab will both take a long time, and be difficult for some students.

–   The proposal must have a model associated with it, and must identify what measures are going to be made and how the data is going to be analyzed.
–   Also, the teacher must be very good at evaluating experiments on the fly. They may think of things that would work, but we haven’t thought of before.

• Possible experiments:

–    Drop the ball from different heights and record the speed at the bottom. They can then make a graph of EIg and Ek and get a linear fit.
–   Also a possibility of rolling things on rails and measuring speeds.

20 min – Whiteboard – Investigating Energy Conservation
PURPOSE: Share experimental designs and results for equations for Eg and Ek

Video Example: (Whiteboarding)

1. What did you learn?
2. What rules can you make?
3. What questions do you still have?

45 min – Board Meeting
PURPOSE: Compare experimental designs and results for Eg and Ek, reach consensus about how to calculate Energies.

Video Examples: (Discussion 1, Discussion 2, Discussion 3)

• Need to define system (Schema)
• Use pie charts to help you determine what needs to be measured
• Strategy 1

–   EIgo – EIgf
–   Plot Ek vs. v
–   Fit a curve in Excel

• Strategy 2

–   EIgo = magh
–   Ekf = m (Dv/Dt)( ½ag(Dt2))
–   Ekf = m (Dv/Dt)( ½(Dv/Dt)(Dt2))
–   Ek = ½mv2
–   Must be supported by data!

• Energy Pie Charts are a representation of the Equation of Everything (energy conservation)

20 min – Whiteboard – 1-d problem using both kinematics and energy conservation
PURPOSE: Compare and contrast strategies for making calculations on constant a model using kinematics and energy;

Problem:

Cubs fan throws his hat straight into the air at 7m/s.

10 min – Board Meeting
PURPOSE: Show how basic constant a models obey energy conservation and give same results.

Emphasize energy as an easy approach that works well in some situations.

60 min – Whiteboard – Redo 2-d problems they’ve already done now using energy &/or additional problems

Energy Pie Chart Problems (Word, Pdf)
Energy Problems for Practice (
Word, Pdf)

Video Examples: (Whiteboarding 2, Discussion 4)

Note: These are often done, but not discussed in a board meeting since they have done them previously.