Sin/cos/tan of theta

1. Dec 2, 2003

BluE

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. Dec 2, 2003

chroot

Staff Emeritus
$\theta$ 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, $\theta$ 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

3. Dec 2, 2003

BluE

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."

Last edited by a moderator: May 1, 2017
4. Dec 2, 2003

chroot

Staff Emeritus
Then you're not talking about theta, you're talking about phi ($\phi$). 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

5. Dec 2, 2003

BluE

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?:

$$F_{cp}=m\omega^2+mg\cos\phi$$

6. Dec 2, 2003

PrudensOptimus

Depends on the situation buddy.

7. Dec 2, 2003

BluE

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?

8. Dec 2, 2003

chroot

Staff Emeritus
9. Dec 3, 2003

BluE

Okay, thank you for your time and help.