Embedded Files
Th 1/9
F 1/10
M 1/13
T 1/14
🟢 5: Th 1/9 - "work"
🟢 5: Th 1/9 - "work"
The concept of “work” is slightly different than the definition we use in every day life. Today, we will review how to calculate work and how this relates to the concept of energy. We will also define gravitational potential energy as well as kinetic energy, and derive equations for both.
Presentation: Work & Energy Presentation (we will try to get through slides 1-22 today)
Optional Extra Practice: Page 1 in Work & Energy Packet. (Unit 6 CompuSheets Answers)
Homework: Assessment on all of Newton's Laws in 2-D Part 2 (projectile motion, gravitation, and circular motion) NEXT CLASS - Monday, January 13th.
🟩❗5: M 1/13 - dynamics in 2-D assessment
🟩❗5: M 1/13 - dynamics in 2-D assessment
Assessment on Newton's Laws in 2-D Part 2 (projectile motion, gravitation, and circular motion) TODAY!
With the remaining time, we will take another look at the Dynamics & Energy Conservation Problems, and make corrections as needed. We'll also discuss how you might calculate the work done to lift an object when the path is not straight up.
Presentation: Work & Energy Presentation (slides 34-35 only)
Homework: Make sure to understand all of the "work" concepts and formulas presented last class. The formulas you should know so far are:
W = Fd cosθ
W = ΔE (will eventually be refined)
Ug = mgh
K = ½ mv²
💚 5: T 1/14 - ↩️Pivot pendulum energy lab (1)
💚 5: T 1/14 - ↩️Pivot pendulum energy lab (1)
Today, we'll do a lab where we investigate how work and energy are related. You'll observe how energy transformations occur in a simple pendulum. You'll learn to use a Vernier photogate timer to find the velocity of the pendulum. The directions for the lab and write-up are located in ↩️ Pivot Interactives "Pendulum Energy Lab." Here's the setup:
Raise the pendulum mass to a height above its lowest (equilibrium) position. Release and measure the velocity as it passes through its lowest position. Repeat for at least 6 different release heights. Graph velocity (m/s) vs. release height (m). Find the mathematical relationship (equation) between velocity and release height, linearizing the graph if necessary.
Analysis question include:
How much work do you do in raising the the pendulum mass?
What forces are on the pendulum as it swings down to equilibrium position? (Draw a free body diagram.) How much work does each of the forces do?
Write a sentence or two about how mechanical energy is transformed from one form to another.
Describe the shape of the velocity vs. height graph. What does this say about the relationship between velocity and release height.
What is the theoretical value of the coefficient in your equation? How does it compare with your experimentally found coefficient?
What assumptions did you make in your experiment? How would these assumptions affect your coefficient that you found in your mathematical relationship?
What is the role of the mass of the pendulum in your equation? Would a better determination of the value of this mass improve the accuracy or precision of this experiment?
Homework: Pendulum energy lab is due in ↩️ Pivot Interactives is due Thursday, January 16th at 10pm. Pendulum Lab assessment Friday, January 17th.
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