Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Hunus

  • 2 years ago

Elastic potential energy

  • This Question is Closed
  1. Hunus
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1335300188613:dw| When does the spring have negative potential energy?

  2. Hunus
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Does it?

  3. Vincent-Lyon.Fr
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Good question! Do you know the expression of this type of potential energy?

  4. Hunus
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    \[\frac{kx^{2}}{2}\]

  5. Vincent-Lyon.Fr
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    So...

  6. Hunus
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Well, when you have the equation \[F_x=-\frac{\partial U}{\partial x}\] what force does F_x represent?

  7. Hunus
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Because if F is the force of the spring, then wouldn't it be positive on the third picture? And if it was positive wouldn't dudx have to be negative?

  8. Vincent-Lyon.Fr
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Your problem is not asking about a negative force, but about a negative energy. For which x can ½kx² be negative?

  9. Hunus
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I'm reading through a book on classical mechanics and I'm having a difficult time understanding when the force is positive\[F_x=−\frac{∂U}{∂x}\]

  10. mos1635
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    when F positive dx is negative??

  11. Vincent-Lyon.Fr
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Draw the function U(x)=½kx² For what values of x is the tangent to the curve positive/negative ? As Fx = -dU/dx, you will know the sign of Fx.

  12. Vincent-Lyon.Fr
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    dU/dx is the derivative of U with respect to x. Its value is the gradient of the tangent to the curve at point (x,U(x)).

  13. Vincent-Lyon.Fr
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Quote : Well, when you have the equation Fx=−∂U/∂x what force does F_x represent? Answer : it reprensents the force exerted by the spring on the block.

  14. Hunus
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thank you

  15. Vincent-Lyon.Fr
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Welcome :)

  16. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.