The period of a simple pendulum, defined as the time necessary for one complete oscillation, is measured in time units and is given by

[tex]\[ T=2 \pi \sqrt{\frac{\ell}{g}} \][/tex]

where [tex]\(\ell\)[/tex] is the length of the pendulum and [tex]\(g\)[/tex] is the acceleration due to gravity, in units of length divided by time squared.

Show that this equation is dimensionally consistent.



Answer :

To show that the equation for the period of a simple pendulum is dimensionally consistent, we start with the given formula:

[tex]\[ T = 2 \pi \sqrt{\frac{\ell}{g}} \][/tex]

Here, [tex]\(T\)[/tex] is the period of the pendulum, [tex]\(\ell\)[/tex] is the length of the pendulum, and [tex]\(g\)[/tex] is the acceleration due to gravity.

### Step-by-Step Solution:

1. Identify the dimensions of each variable:

- [tex]\(T\)[/tex]: Time period (measured in units of time, i.e., [tex]\( [T] \)[/tex]).
- [tex]\(\ell\)[/tex]: Length of the pendulum (measured in units of length, i.e., [tex]\( [L] \)[/tex]).
- [tex]\(g\)[/tex]: Acceleration due to gravity (measured in units of length per time squared, i.e., [tex]\( [L/T^2] \)[/tex]).

2. Rewrite the equation using the dimensions:

Substitute the dimensions into the equation:

[tex]\[ [T] = 2 \pi \sqrt{\frac{[\ell]}{[g]}} \][/tex]

3. Substitute the dimensions of [tex]\(\ell\)[/tex] and [tex]\(g\)[/tex]:

[tex]\[ [T] = 2 \pi \sqrt{\frac{[L]}{[L/T^2]}} \][/tex]

4. Simplify the fraction inside the square root:

[tex]\[ [T] = 2 \pi \sqrt{\frac{[L]}{[L] / [T^2]}} \][/tex]

Simplifying the division inside the square root:

[tex]\[ \frac{[L]}{[L] / [T^2]} = \frac{[L] \cdot [T^2]}{[L]} = [T^2] \][/tex]

5. Take the square root of [tex]\([T^2]\)[/tex]:

[tex]\[ [T] = 2 \pi \sqrt{[T^2]} = 2 \pi [T] \][/tex]

6. Check the consistency:

Since [tex]\(2 \pi\)[/tex] is a dimensionless constant, it does not affect the overall dimensions. Therefore:

[tex]\[ [T] = [T] \][/tex]

This shows that the dimensions on both sides of the equation are the same. Therefore, the equation is dimensionally consistent, as both sides have the dimension of time ([tex]\([T]\)[/tex]).

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