Masses hanging from ceilings by strings

  • Thread starter gedanken6
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In summary, two strings, A and B, are attached to a large suspended mass from the ceiling and the bottom of the mass, respectively. The question is which string would break first when string B is pulled sharply or steadily. Using a 2-pound hammer and two fish scales, it was found that string A would break first. However, when using a thin string instead of a stout cord, string B broke first. This suggests that the answer may depend on the type of string used and other factors such as impulse. Overall, this experiment provides a hands-on approach to understanding the concept of forces and their effects on objects.
  • #1
gedanken6
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Homework Statement


A body of large mass is suspended by means of a string A from the ceiling, and another similar string B is attached to the bottom of the body. Which string would break when string B is pulled (a) sharply, and (b) steadily? Why?


Homework Equations


F=ma



The Attempt at a Solution


I assume string B would break first. I'm not sure why. On string A, I've labelled T with an arrow going one way, and one going the opposite way on the string. This seems vaguely familiar to me. I've drawn an arrow from the large down labelled g. Unfortunately, I'm not very good at this sort of thing, but I want to become a pro.
 
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  • #2
Well, this is not going to be helpful with the problem as a homework assignment, but it was interesting.

Using a 2-pound hammer, and two fish scales (range 0-8 pounds) with a stout cord, gives these results. Let A,B denote the forces in their respective strings. When B=0 (no pull on string B), A = 2. If B=4, then A=6. If B=6, then A=8. So that suggests string A would break first. Did not test to breakage point - might have damaged the fish scales.

On the other hand, using the same setup but with a thin string not a stout cord, string B broke first whether additional force was applied gradually or suddenly. Only one trial was made for each speed of force application. Possibly related to non-uniformity in the two thin strings, though they were from the same spool.

Anyway, a nice little "you can do this at home" experiment. Suggests trying other configs, not just linear, making these problems more than textbook paper exercises. Thanks!
 
  • #3
Have you tried impulse?
 

1. What causes a mass to hang from a ceiling by a string?

The force of gravity is what causes a mass to hang from a ceiling by a string. The mass is pulled towards the center of the Earth due to the Earth's gravitational pull, and the string provides a tension force that balances out the weight of the mass, keeping it suspended.

2. How does the length of the string affect the hanging mass?

The length of the string affects the hanging mass by changing the magnitude of the tension force. The longer the string, the greater the tension force required to hold the mass in place. This is because a longer string has more slack and can stretch more, which requires a stronger force to balance out the weight of the mass.

3. What is the relationship between the mass and the tension force in a hanging system?

The relationship between the mass and the tension force in a hanging system is directly proportional. This means that as the mass increases, the tension force must also increase to keep the mass suspended. If the mass is doubled, the tension force must also be doubled to maintain equilibrium.

4. Can the angle of the string affect the hanging mass?

Yes, the angle of the string can affect the hanging mass. The tension force in the string is split into horizontal and vertical components, with the vertical component supporting the weight of the mass. As the angle of the string increases, the vertical component decreases, which means the tension force must increase to keep the mass suspended.

5. How does the type of string used affect the hanging mass?

The type of string used can affect the hanging mass by changing the strength and elasticity of the string. A stronger and less stretchable string can support a larger mass compared to a weaker and more stretchable string. Additionally, the type of material used can also affect the weight and thickness of the string, which can impact the tension force required to hold the mass in place.

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