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# Compound pendulum Watch

1. Hi everyone,

I have a question for you. how do you calculate the value of the acceleration due to gravity using the compound pendulum experiment?

I know how to do the experiment, I just don't understand how you plot the graph for it, and how you use the graph to determine the value of g. Can anyone please explain what you're supposed to do?

Thanks a lot
2. (Original post by mrambitious)
Hi everyone,

I have a question for you. how do you calculate the value of the acceleration due to gravity using the compound pendulum experiment?

I know how to do the experiment, I just don't understand how you plot the graph for it, and how you use the graph to determine the value of g. Can anyone please explain what you're supposed to do?

Thanks a lot
GPE = KE
mgh = 0.5mv^2
g=(0.5v^2)h
3. (Original post by NNB_Herath)
GPE = KE
mgh = 0.5mv^2
g=(0.5v^2)h
I am still kind of stuck, could you please explain the steps so that I can understand what I meant to do?
4. (Original post by mrambitious)
Hi everyone,

I have a question for you. how do you calculate the value of the acceleration due to gravity using the compound pendulum experiment?

I know how to do the experiment, I just don't understand how you plot the graph for it, and how you use the graph to determine the value of g. Can anyone please explain what you're supposed to do?

Thanks a lot
Can you give details of your compound pendulum? The first thing that comes to mind is simply to measure its period like a normal pendulum but adjust the formula for the period - you can look this up or ask me, but you'd need to know the exact construction of the pendulum (e.g. 200g rod with 500g ball at the end etc)
5. (Original post by mrambitious)
I am still kind of stuck, could you please explain the steps so that I can understand what I meant to do?
what they've done there is equal gravitational potential energy to kinetic energy then use what they're equal to get to the middle equation then rearrange for g

where gpe=mgh and ke=0.5mv^2
if ke=gpe
then 0.5mv^2=mgh
rearrange for g
6. ..
7. ..
8. update:

I now understand what you're supposed to do with the graph and how you find the value of g from it.

I appreciate everyone's help.
9. (Original post by mrambitious)
update:

I now understand what you're supposed to do with the graph and how you find the value of g from it.

I appreciate everyone's help.
Can you explain so we can correct ourselves if we are wrong ?

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