# Period of a simple pendulum with a magnet under it

• MatinSAR
In summary, the conversation is about a disagreement over the value of F/mg in a physics problem involving a magnet and an iron ball. One person thinks it is 3, while another thinks it is 4. There is also a mention of eddy currents and a breakthrough in metallurgy. The conversation ends with an apology for a failed attempt at humor and an agreement on the answer.
MatinSAR
Homework Statement
The period of a simple pendulum with an iron ball is T. If we put a magnet under it, its period becomes T/2. What is F/mg equal to?(F is the force that is exerted by the magnet.)
Relevant Equations
T = 2π Square root of√L/g
Hi ...
I have answered this question and I think that F/mg equals 3.
But I've asked it from someone and he told me that F/mg is 4.
Can someone help me find out which one is correct ???

I'm with you.
My guess is the other solver forgot gravity still acts when the magnet is present.

MatinSAR
haruspex said:
My guess is the other solver forgot gravity still acts when the magnet is present.
Yes he said he ignored gravity.

Just to be nit picking, there would be an additional force due to eddy currents induced in the iron ball as it swings past the magnet that will damp the motion.

MatinSAR
kuruman said:
Just to be nit picking, there would be an additional force due to eddy currents induced in the iron ball as it swings past the magnet that will damp the motion.
Owing to a breakthrough in metallurgy, it is superconducting.

malawi_glenn and MatinSAR
kuruman said:
Just to be nit picking, there would be an additional force due to eddy currents induced in the iron ball as it swings past the magnet that will damp the motion.
What if we ignore eddy currents ? Because if it is not omitted, the periodicity is not defined for movement.
Do you agree with F/mg=3 in this case ?

haruspex said:
Owing to a breakthrough in metallurgy, it is superconducting.
I didn't understand ...
Can you please tell me if you disagree with my answer ...

MatinSAR said:
I didn't understand ...
Can you please tell me if you disagree with my answer ...
It was just an attempt at a humorous response to @kuruman's nitpick.

MatinSAR
haruspex said:
It was just an attempt at a humorous response to @kuruman's nitpick.
I understand ...
Thanks again ...

I too agree with your answer. I am sorry that my attempt at levity confused you.

MatinSAR
kuruman said:
I too agree with your answer. I am sorry that my attempt at levity confused you.
I'm sorry I'm not a native speaker of English and this is why I didn't understand.
Thank you ...

## 1. What is a simple pendulum with a magnet under it?

A simple pendulum with a magnet under it is a type of pendulum that has a magnet attached to its bottom end. The magnet interacts with a magnetic field, causing the pendulum to behave differently than a traditional pendulum.

## 2. How does the presence of a magnet affect the period of a simple pendulum?

The presence of a magnet under a simple pendulum changes the period of the pendulum. The magnet's magnetic field alters the pendulum's natural frequency, causing it to oscillate at a different rate.

## 3. What factors influence the period of a simple pendulum with a magnet under it?

The period of a simple pendulum with a magnet under it is influenced by several factors, including the strength of the magnet, the strength of the magnetic field, the length of the pendulum, and the mass of the pendulum.

## 4. How can the period of a simple pendulum with a magnet under it be calculated?

The period of a simple pendulum with a magnet under it can be calculated using the equation T = 2π√(L/g), where T is the period, L is the length of the pendulum, and g is the acceleration due to gravity. This equation can be modified to include the effects of the magnet and magnetic field.

## 5. What are some real-world applications of a simple pendulum with a magnet under it?

A simple pendulum with a magnet under it has several real-world applications, including use in magnetic compasses, seismometers, and accelerometers. It can also be used to study the effects of magnetic fields on pendulum motion and to demonstrate principles of physics in educational settings.

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