See Saw Balance: Heavy Person & Fulcrum

  • Thread starter Lula Belle
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In summary, the conversation discusses the concept of balance on a seesaw, specifically when one person weighs more than the other. The question is asked whether the heavier person needs to move closer to the fulcrum to balance out the weight. Two different ways of thinking about the problem are presented: intuitively and mathematically. The conversation also acknowledges the limitations of the person asking the question and suggests a simple experiment to understand the concept better. An applet is also provided for further exploration.
  • #1
Lula Belle
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on a see saw when one person weighs much more than the other, does the heavier person need to move closer to the fulcrum to balance out the weight?
 
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  • #2
Go to a park and try it.
 
  • #3
I am so sorry to ask such a dumb question. I have a medical condition which prevents me from being able to figure things out as well as I used to. Please forgive me.
 
  • #4
Thinking intuitively:
Think about two people with equal weights. In this situation, obviously to make them balance each other on a seesaw they would need to be the same distance away from the fulcrum.
Imagine then that one of those people (Let's say Person A) moves closer to the fulcrum (pivot). Which direction would the see saw move?

Thinking mathematically:
Torque = Force x r
r being the distance from the pivot point.

To make the seesaw balanced the torque by person A would have to be the same as the one for person B. If person A's weight is bigger, then what do you have to do to r to make it stay constant?
 
  • #5
Lula Belle said:
I am so sorry to ask such a dumb question. I have a medical condition which prevents me from being able to figure things out as well as I used to. Please forgive me.

It is not a dumb question and I did not mean to be insensitive to your medical condition. Much of basic physics can be revealed by simple experiment and I meant to suggest that. I don't know your limitations, but you might be able to find a simple object, for example a metal kitchen ladle, where one end has much more mass than the other (or the mass is more concentrated). Then try balancing it on your finger (or on a pencil or the edge of something). Is the balance point closer to the "heavy" end or the light one?
Tom
 
  • #6
Lula Belle said:
I am so sorry to ask such a dumb question. I have a medical condition which prevents me from being able to figure things out as well as I used to. Please forgive me.

And, here is an applet that allows you to "play" with this sort of question. Many people find that trying something out makes the equations more sensible.
http://www.walter-fendt.de/ph11e/lever.htm
Tom
 
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1. How does a see-saw balance work?

A see-saw balance works by utilizing the principles of leverage and balance. The heavy person on one side of the fulcrum provides a greater weight, while the lighter person on the other side provides a smaller weight but is positioned further away from the fulcrum. This creates an unequal distribution of weight, causing the see-saw to tilt towards the heavier person. As the heavier person goes down, the lighter person goes up, and vice versa, creating a back-and-forth motion.

2. What is the purpose of the fulcrum in a see-saw balance?

The fulcrum acts as the pivot point or point of support for the see-saw. It is typically placed at the center of the see-saw and allows for the see-saw to rotate around it. Without a fulcrum, the see-saw would not be able to balance and would simply fall to the ground.

3. Why does the heavy person always go down while the lighter person goes up?

This is due to the principle of leverage. The heavy person is positioned closer to the fulcrum, which means their weight is exerted over a shorter distance. The lighter person, on the other hand, is positioned further away from the fulcrum, which means their weight is exerted over a longer distance. This creates an unequal distribution of weight, causing the see-saw to tilt towards the heavier person.

4. Can a see-saw balance with two people of equal weight?

Yes, it is possible for a see-saw to balance with two people of equal weight. However, the placement of the people on the see-saw must be carefully adjusted so that they are positioned at equal distances from the fulcrum. This ensures that the weight on both sides is balanced, and the see-saw remains level.

5. How does the distance of the fulcrum from the center affect the balance of a see-saw?

The distance of the fulcrum from the center of the see-saw affects the balance by changing the amount of leverage exerted by each person. A fulcrum placed closer to one end of the see-saw will give that side a greater advantage and cause it to go down, while the other side will go up. By moving the fulcrum closer or further away from the center, the see-saw can be balanced or tilted in favor of one side.

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