Calculating g from formula for period of pendulum

In summary: Finally, we can plug in the value for T_0 that we calculated from the given data:T_0 = \frac{T(\phi_{max})}{1 + \frac{1}{16}\phi_{max}^2}T_0 = \frac{1.99433 \pm 0.00005}{1 + \frac{1}{16}(0.010 \pm 0.005)^2} = 1.99433 \pm 0.00005Now, we can substitute this value into our equation for \delta g:\delta g = \sqrt{\left(-\frac{4 \pi^2}{(1.99433)^3}\
  • #1
Shukie
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Homework Statement


I want to calculate g from the formula for the period of a pendulum. The trouble is the uncertainties.

Homework Equations


[tex]g = \left(\frac{2 \pi}{T_0}\right)^2 L[/tex]

[tex]T_0 = \frac{T(\phi_{max})}{1 + \frac{1}{16}\phi_{max}^2}[/tex]

[tex]T(\phi_{max}) = 1.99433 \pm 0.00005 \ \mathrm{s}[/tex]

[tex]\phi_{max} = 0.010 \pm 0.005[/tex] (radians)

[tex]L = 0.98967 \pm 0.00002[/tex]

The Attempt at a Solution



I really have no idea. Do I use error propagation?
 
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  • #2




Thank you for your question about calculating g from the formula for the period of a pendulum. You are correct in thinking that error propagation is necessary in this calculation. The formula for g involves several variables, each with their own uncertainties, so it is important to properly account for these uncertainties in the final result.

To begin, let's rewrite the formula for g in terms of the variables given in the problem:

g = \left(\frac{2 \pi}{T_0}\right)^2 L

We can then use the rules of error propagation to calculate the uncertainty in g. The general formula for error propagation is given by:

\delta g = \sqrt{\left(\frac{\partial g}{\partial x_1}\right)^2 \delta x_1^2 + \left(\frac{\partial g}{\partial x_2}\right)^2 \delta x_2^2 + ... + \left(\frac{\partial g}{\partial x_n}\right)^2 \delta x_n^2}

where \delta g is the uncertainty in the final result, \delta x_i is the uncertainty in each variable x_i, and \frac{\partial g}{\partial x_i} is the partial derivative of g with respect to x_i.

Applying this formula to our problem, we get:

\delta g = \sqrt{\left(\frac{\partial g}{\partial T_0}\right)^2 \delta T_0^2 + \left(\frac{\partial g}{\partial L}\right)^2 \delta L^2}

To simplify the calculation, we can first calculate the partial derivatives of g with respect to each variable:

\frac{\partial g}{\partial T_0} = \left(\frac{2 \pi}{T_0}\right)^2 \frac{-2 \pi}{T_0^2} = -\frac{4 \pi^2}{T_0^3}

\frac{\partial g}{\partial L} = \left(\frac{2 \pi}{T_0}\right)^2

Next, we can substitute in the values and uncertainties for each variable:

\delta g = \sqrt{\left(-\frac{4 \pi^2}{T_0^3}\right)^2 (0.00005)^2 + \left(\frac{2 \pi}{T_0}\right)^2 (0
 

FAQ: Calculating g from formula for period of pendulum

What is the formula for calculating the period of a pendulum?

The formula for calculating the period of a pendulum is T = 2π√(L/g), where T is the period, L is the length of the pendulum, and g is the acceleration due to gravity.

What is g and how is it related to the period of a pendulum?

g is the acceleration due to gravity, which is a constant value of 9.8 m/s^2 on Earth. It is related to the period of a pendulum because the period is directly proportional to the square root of the length of the pendulum and inversely proportional to the square root of g.

How do you calculate the value of g using the period of a pendulum?

To calculate the value of g using the period of a pendulum, you can rearrange the formula T = 2π√(L/g) to solve for g. This would give you g = 4π^2L/T^2. Simply plug in the known values for T and L to solve for g.

Are there any factors that can affect the accuracy of calculating g from the period of a pendulum?

Yes, there are a few factors that can affect the accuracy of calculating g from the period of a pendulum. These include air resistance, the angle at which the pendulum is released, and the precision of the measurements for T and L.

Can the formula for calculating g from the period of a pendulum be used on other planets?

Yes, the formula T = 2π√(L/g) can be used on other planets as long as the value of g on that planet is known. However, the value of g may differ on other planets due to variations in mass and radius, so the formula may need to be adjusted accordingly.

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