Please explain this question on Acceleration due to gravity detail ?

Which one of the following is better way to measure the Acceleration due to gravity '#g#' ?

  1. Bar Pendulum or 2. Simple Pendulum

1 Answer
Mark C.
Jan 5, 2018

Simple pendulum - the Maths is simpler, hence uncertainty is lower in general.

Explanation:

Using the period, #T = 2pisqrt(l/g)# means you only have 2 variables and the uncertainty in T is easily reduced by measuring multiple oscillations (say 20 or 50 periods) and averaging. The value of ‘l’ is more tricky, just make sure you measure from the exact upper pivot to the CofG of the mass.

Keeping the amplitude as low as practical and measuring to a fiduciary point are your only other issues, i think. You must state your assumptions (light inextensible string, etc etc.) but that’s not complex.

Using a bar pendulum is significantly more complex (“a nightmare” was my description the only time I tried it.) The equations and method can be found here: https://dkpandey.weebly.com/uploads/1/3/5/3/13534845/bar_pendulm.pdf

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