Download week thirteen

**In Class Activity Plan**

**90 min – Investigating Spring Forces** (Word, Pdf)

PURPOSE: Investigate situation that can’t be modeled with constant acceleration, introduce Hooke’s Law; introduce relationship between forces and energy.

Video Example: (Predictions)

*Technical Notes:*

- The force sensors need to have their direction reversed so that both the motion sensor and the force sensor see the same direction as positive
- We probably want each group to have a different spring
- They’re going to be coming back to energy at the end of this lab using the force versus displacement graph and the energy stored in the spring

*Seed:*

- Consider the situation of a person just constantly stretching the spring

o Draw pie charts for this situation

o Where does the energy from the person go?

**10 min – Whiteboard Investigating Spring Forces**

PURPOSE: Summarize results of investigation

Video Examples: (Boarding 1, Boarding 2)

- What did you learn?
- What rules can you make?
- What questions do you still have?

**45 min – Whiteboard Discussion**

PURPOSE: Investigate situation that can’t be modeled with constant acceleration, introduce Hooke’s Law; introduce relationship between forces and energy.

Video Example: (Discussion)

*Goals:*

- Hooke’s Law

o

o The slope of the F vs d graph is the spring constant

- Energy stored in the spring

o Consider the units of the area under the F vs d curve (get to energy stored in the spring)

o Need to point out this is negative (and makes sense b/c the integral is negative)

**20 min – Whiteboard – Spring problems (2): Compression Spring** (Word, Pdf)** & Crates from a spring** (Word, Pdf)

PURPOSE: Practice modeling situations using Hooke’s law, integrating non constant acceleration situations into existing models.

*Note: Do *one in class and assign the other for homework

**25 min – Board Meeting**

PURPOSE: Build consensus around modeling situations using Hooke’s law, integrating non- constant acceleration situations into existing models.

Video Examples: (Boarding 3, Boarding 4, Boarding 5)

**40 min – Instructor led discussion – Thinking about circular motion**

PURPOSE: Introducing circular motion, special type of constant a modeling.

Video Example: (Four perspectives)

*Using bowling balls and rubber mallets:*

- Ask the students, how would you have to hit the ball in order to get it to move in a circle? Try it.
- Should find that they need to hit the balls toward the center of the circle (or perpendicular to the motion or something similar).
- Confirm with video from Rutgers: Visit website
- Have the students make a motion map for the ball
- Divide the class in quarters, and have each of them find the direction of the acceleration for each ¼ of the motion map on their whiteboard

o They already know about impulse, so it might be useful for them to be thinking about the force that is changing the momentum in this case

**30 min – Whiteboard Discussion**

PURPOSE: Use motion maps to determine uniform circular motion as a special case of a constant acceleration model.

- Looking at each sections acceleration and force diagrams, what can we say about the direction of the acceleration? The net force?
- Either show the geometric derivation of the centripetal acceleration or give the handout to get to