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🟢 8: T 1/20 - 📖 work & energy conservation problems
🟢 8: T 1/20 - 📖 work & energy conservation problems
Today, we'll work on problem solving for energy conservation (Wnc ≠ 0).
Optional Extra Practice: 📖 textbook problems from chapter 10 on energy conservation #35, 37, 39, 42, 43, 47, 49, 79. Also, Work & Energy Packet page 4 #1-5 (Solutions to FYP: Energy).
Homework: Finish problem solving. Quiz on work and energy conservation problems (Wnc = 0 & Wnc ≠ 0) on Thursday, January 22nd.
🟩 8: W 1/21 - 📄 Hooke's Law Lab
🟩 8: W 1/21 - 📄 Hooke's Law Lab
Today, we’ll investigate how springs behave and learn about Hooke’s Law through an exploratory lab. In the lab, you’ll try to answer the following questions:
Is the force that a spring applies constant?
If so, what is the force for a given spring? If not, how does the force change?
Is there energy associated with a spring? In other words, can a spring do work?
If so, how can you calculate the work done by a spring?
Handout: 📄 Hooke's Law Lab
Homework: Finish the 📄 Hooke's Law Lab worksheet. It will be collected at the beginning of next class on Thursday, January 22nd. Quiz on work and energy conservation problems (Wnc = 0 & Wnc ≠ 0) next class - Thursday, January 22nd.
💚❗8: Th 1/22 - 📖elastic potential energy
💚❗8: Th 1/22 - 📖elastic potential energy
Quiz on work and energy conservation problems (Wnc = 0 & Wnc ≠ 0) TODAY.
Today, after the quiz, we'll start by thinking about reviewing Hooke's Law Fe = -kx where x is the displacement from a spring's equilibrium position. We'll learn that for certain springs that obey Hooke's Law, the elastic force is proportional to the amount of stretch or compression. The proportionality constant k is called the "spring constant" and is measured in units N/m. The elastic force is a conservative force. The negative sign in Hooke's Law indicates that the force is in the opposite direction to the displacement from the equilibrium position, but when we plug into our ΣF statement, we'll just use the magnitude |Fe|= kx since the direction will be accounted for in the + or - before the force.
Then, we'll learn that to find the energy stored in the spring, we need to take the area under this curve which gives us: Ue = ½ kx2. We'll include this potential energy into our before & after diagrams by including a third question:
Is the object moving? (kinetic energy)
Is the object above or below our potential energy = 0 height? (gravitational potential energy)
Is there a spring that is stretched or compressed? (elastic potential energy)
Finally, we'll review what we've learned about Hooke's Law and elastic potential energy by doing problems from 📖 textbook chapter 10 on elastic potential energy #24, 25, 48.
Optional Extra Practice: PedersonScience.com.
Homework: Finish the problem solving. Write out a solution for the third video below and upload it to ✏️Google Classroom also by Sunday at 10pm. Assessment on all of Work and Energy on Wednesday, January 28th.
If for some reason you missed class today or you need a review, check out the following videos from Dan Fullerton:
Watch examples during time 7:45-11:05 only, unless you want more practice with other conservation of energy problems.
Finally, here's a more complex example like what you'd see on a test. (Think about how you'd do this with our Before & After diagram and our conservation of energy equation. Remember that the spring force is a conservative force.) Write out your solution to this problem and submit it to ✏️ Google Classroom by Monday, January 26th at 10pm.
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