A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Agent_A

  • one year ago

See photos below.

  • This Question is Closed
  1. Agent_A
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Why was my initial answer wrong? I don't get what it's asking, about the correct phase angle. I tried to use the degree mode, to get the reflex angle, and convert the reflex angle to radians, but I did not get the correct answer.

    2 Attachments
  2. Agent_A
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    3.72 rad is correct, but I have no idea how that was solved.

  3. Agent_A
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Ooops I forgot to attach the question for that part. Here it is: What is the value of the phase angle ϕ if the initial velocity is positive and the initial displacement is negative?

  4. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    hint: the displacement x(t) and speed x˙(t) of the object, can be modeled by these functions: \[\Large \begin{gathered} x\left( t \right) = A\sin \left( {\omega t + \phi } \right) \hfill \\ \dot x\left( t \right) = A\omega \cos \left( {\omega t + \phi } \right) \hfill \\ \end{gathered} \] please note that the second equation is obtained from the first one, making the first derivative with respect to time of such first equation. Now from your data, we ca write: \[\Large \begin{gathered} U = \frac{1}{2}kx_0^2\quad \Rightarrow {x_0} = - \sqrt {\frac{{2U}}{k}} \hfill \\ \hfill \\ T = \frac{1}{2}m\dot x_0^2\quad \Rightarrow {{\dot x}_0} = \sqrt {\frac{{2T}}{m}} \hfill \\ \end{gathered} \] where \( \Large U,T\) are the potential and kinetic energy respectively, whereas \(\Large {x_0}, {{\dot x}_0}\) are the coordinate of position and the speed of the object at \( \Large t=0\). Now, at \( \Large t=0\), substituting, we have: \[\Large \begin{gathered} x\left( 0 \right) = A\sin \left( \phi \right) \hfill \\ \dot x\left( 0 \right) = A\omega \cos \left( \phi \right) \hfill \\ \end{gathered} \] so, after a simple substitution, we get the subsequent algebraic system: \[\Large \left\{ \begin{gathered} - \sqrt {\frac{{2U}}{k}} = A\sin \left( \phi \right) \hfill \\ \hfill \\ \sqrt {\frac{{2T}}{m}} = A\omega \cos \left( \phi \right) \hfill \\ \end{gathered} \right.\] please solve that system with respect to \( \Large \phi \), and \( \Large A \), and you will find your correct answers. Of course \( \Large A \) is the amplitude of the motion of the object

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

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

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.