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Sin/cos/tan of theta

  1. Dec 2, 2003 #1
    Hello, I'm studying pendulums and their proporties, and I really need to know the sin/tan/cos of theta. If anyone can help, please help. (And also, I need to know what theta is)

    And if you don't understand what I'm asking, please ask and I'll try to explain to the best of my ability.

    --Thank you
  2. jcsd
  3. Dec 2, 2003 #2


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    [itex]\theta[/itex] is a symbol commonly used to denote an angle. What angle? I don't know, you'd have to tell me, since you're the one looking at the problem. Most likely, for a pendulum problem, [itex]\theta[/itex] means the angle between the pendulum's string and a vertical line. This angle is constantly changing as the pendulum swings back and forth.

    The sine, cosine, and tangent are functions. They're like little machines: you give them an angle, and they give you back a number. For example, the cosine of zero degrees is one: if you insert "zero degrees" into the "cosine machine," it spits out the number "one."

    Maybe you should post the entire problem for us here so we can better help you.

    - Warren
  4. Dec 2, 2003 #3
    Actually, there is no problem, I just don't know what is being talked about. (I really don't know if I even explained it right to you)

    http://www.gyogyitokezek.hu/fe/pendtutor1.htm [Broken]

    This is a sight, and the one I'm looking at is the "plane pendulum."

    Thanks for your help!
    Last edited by a moderator: May 1, 2017
  5. Dec 2, 2003 #4


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    Then you're not talking about theta, you're talking about phi ([itex]\phi[/itex]). The meaning of this symbol is shown in Fig. 2 on the site. It is the angle of the pendulum, measured anticlockwise with respect to some point on the circle (shown there on the bottom of the circle).

    - Warren
  6. Dec 2, 2003 #5
    Okay, thanks. But I have another question. If I were to make a pendulum to exert force on an object, how do I calculate how much force the pendulum has and how could I control it?

    Do I use this equation?:

  7. Dec 2, 2003 #6

    Depends on the situation buddy.
  8. Dec 2, 2003 #7
    Okay, say I have a plane pendulum and I want to use it to make contact with a stationary object, thereby causing motion to the object. How do I calculate how much force the pendulum exerts and how can I control it? Say, I know "x" amount of force is needed to move an object from point A to point B. How can I use the pendulum to control and calculate "x" amount of force to give motion to the object?
  9. Dec 2, 2003 #8


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  10. Dec 3, 2003 #9
    Okay, thank you for your time and help.
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