# Equation Confusion

1. May 10, 2008

### Air

I've come across a equation and I don't understand whether $T$ is Time/s or Tension/N. Can someone explain this equation:

$T = 2 \pi \sqrt{\frac{l}{g}}$

Thanks in advance.

2. May 10, 2008

### silver-rose

That would be the equation for the simple harmonic motion of a hanging mass on a pendulum.

T denotes the period of oscillation,
l the length of the string on which the mass hangs.

Notice that the period doesn't depend on how "wide" the mass swings.

3. May 10, 2008

### Volcano

it is time. In fact period. Put the units for them and calculute the final result.

l : m/s
g: m/s^2

(m/s) / (m/s^2) : s

4. May 10, 2008

### Air

Isn't Period equal to:

$P = \frac{1}{T}$

So to calculate time of oscillation, $T$ would need to be made subject.

5. May 10, 2008

### Volcano

frequence : 1/s
period : s

6. May 10, 2008

### HallsofIvy

Staff Emeritus
No, a "period" is a certain length of time and so has the same units as T (whatever "T" means here). The formula you give is for "frequency"- the number of times the pendulum swings during 1 second and so has units of "1/sec".

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