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Energy Conservation in Springs Review Questions

Practice questions on energy conservation involving momentum, kinetic energy, potential energy, power, springs, and more. Understand the principles behind energy conservation in physics.

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Energy Conservation in Springs Review Questions

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  1. PHYS16 – Lecture 17 Energy Conservation: Springs October 18, 2010

  2. Review

  3. Practice Question 1 • If the momentum of an object increases by 4 fold, how much does the kinetic energy of the object change by? • 1/16 • ¼ • 2 • 4 • 16

  4. Practice Question 2 • If the potential energy of a 5 kg book is 100 J, what is the height of the book? • 2 m • 1 m • 20 m • 10 m • There is not enough information

  5. Practice Question 3 • If a car engine for a 1400 kg car outputs 1000 kW of average power, how much time does it take to accelerate from 0 to 25 m/s? • 0.4 s • 1 s • 0.2 s • 0.8 s • 10 s

  6. This Week • Spring Force and Energy • Conservative vs. Nonconservative Forces • Conservation of Energy • Sleds and Rollercoasters • Springs • Pendulums

  7. Springs

  8. Spring Force and Energy • Spring Force • Spring Energy http://ux1.eiu.edu

  9. What is the Energy of this system? Assume x=0 at Equilibrium point then… http://sparknotes.com

  10. What is the Energy of this system? Approach #1 Assume x=0 at Equilibrium point then… Approach #2 Assume x=0 at ground then… http://sparknotes.com Accounting for zero point not at equilibrium

  11. Zero of Potential Energy • Wherever you set your zero point for potential energy will determine your coordinate system • U=0 J at y=0 point for gravitational pot. energy • U=0 J at equilibrium point for spring pot. Energy • All calculations of ΔU will be relative so it won’t matter where you put 0 J just make sure not to switch back and forth!!!

  12. Energy Conservation

  13. Conservative vs. Nonconservative Forces • Conservative Forces– force where work done over ANY closed path is zero WAtoB= -WBtoA WAtoB, path 1 = WAtoB, path 2 • Nonconservative force – not conservative

  14. Is Gravity a conservative Force? • Let’s assume two different paths and see if we get the same work… Path #1 Path #2 Yes, so gravity is conservative!

  15. Is the spring force conservative? • Let’s assume two different paths and see if we get the same work… Path #1 Path #2 Yes, so spring force is conservative!

  16. Is friction conservative? • Let’s assume two different paths and see if we get the same work… Path #1 Ff Ff Path #2 Ff No, so friction is nonconservative…

  17. Conservative vs. Nonconservative Forces • Conservative • Spring Force • Gravity • Buoyant Force • Nonconservative • Friction • Air resistance/Drag • Fluid resistance • Applied Forces Situation Dependent Tension Normal Force

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