How does temperature affect grandfather clocks with brass pendulums?

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In summary, grandfather clocks with brass pendulums are highly sensitive to changes in temperature due to the pendulum's length changing with temperature, which is directly affected by the metal expansion coefficients. To overcome this, compensation methods involving keeping the length constant at which the effective mass swings can be used, but this requires ingenuity and the use of materials with different coefficients. The first accurate clock, created in a competition to aid navigation on ships, also incorporated similar compensation methods. The inventor of this clock was John Harrison of England. The coefficient of expansion for brass is 10.4 x 10^-6 in/in °F, compared to 6.7 x 10^-6 in/in °F for unalloyed iron.
  • #1
Science_and_math
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Grandfather clocks with brass pendulums tend to be very sensitive to changes in temperature.
1. WHY?
2. What can be done to overcome this?
 
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  • #2
how does the coefficient of expansion for brass compare to that of other metals say?
 
  • #3
compensation

Pendulums change period because their length changes with temperature
due directly to metal expansion coefficients.
Compensation methods involve keeping the length at which the effective mass swings at a constant distance from the fulcrum this generally requires a lot of ingenuity and can involve materials with different coefficients .
Ray
 
  • #4
If I had to take a guess I would say the specific heat of that with the brass.
 
  • #5
To bionic -- specific heat is not the same as expansion
To Norm -- you can always look this up on the internet as 'physical constants'
To all -- the history of clocks is fascinating and I think that the first accurate clock was created in a competition to make a navigation aid on board ships -- this was not a pendulum but it did incorporate various compensation means for temperature and motion -- sorry for the moment I cannot recall the inventor -- very famous , but I am sure you can search this if interested.
Ray
 
  • #6
rayjohn01 said:
To Norm -- you can always look this up on the internet as 'physical constants'.

The question I posed was to help the original poster think about what is going on with the pendulum. Typically on this forum you have a lot of students asking questions about homework. It is always best to try and lead them to an answer through posing related question they can answer along the way to the solution instead of just telling them the answer. Students tend to remember solving a problem better when they figure them out on their own compared to being given an answer.
Cheers,
Norm
 
  • #7
Rayjohn01, the person you are thinking about is John Harrison of England. He invented his clocks in the cause to solve the longitude problem of the day. As far as I know they were spring driven since pendulums on rocking ships did not work well at all.

The alpha for brass is about 10.4 x 10^-6 in/in °F. Compare that to the alpha for un alloyed iron at 6.7 x 10^-6 in/in °F.

Specific heat of the material is not a factor (as was stated before).
 

FAQ: How does temperature affect grandfather clocks with brass pendulums?

What is a pendulum?

A pendulum is a weight suspended from a fixed point that swings back and forth under the influence of gravity.

What is the purpose of a pendulum?

A pendulum can be used to measure time, as the time it takes for the pendulum to swing back and forth is constant and can be used to create accurate timekeeping devices.

How does the length of a pendulum affect its movement?

The length of a pendulum affects its movement by changing the period, or time it takes for one complete swing. Longer pendulums have a longer period and shorter pendulums have a shorter period.

How does the weight of a pendulum affect its movement?

The weight of a pendulum does not affect its movement, as long as the weight is concentrated at the end of the pendulum and does not change during the swing.

What factors can affect the movement of a pendulum?

The movement of a pendulum can be affected by factors such as air resistance, friction, and the angle of release. These factors can cause the pendulum to swing at a slightly different rate than predicted by mathematical equations.

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