Finding the unstretched length of a bungee cable

Since at the bottom of the drop, the potential energy will be converted to kinetic energy, and then back to potential energy at the peak of the bounce.In summary, two men who weigh 150lb each jump off a bridge using a bungee cord with stiffness k=80lb/ft. One man is attached to the cord and plans to release the other man when they reach the water 120ft below. The unstretched length of the cord is determined to be 90ft. To determine the maximum acceleration of the attached man and the maximum height he reaches above the water when he springs back up, conservation of energy can be used again, as the potential energy at the bottom of the drop will be converted to kinetic energy and
  • #1
jbrizown
2
0
Two men both weighing 150lb jump off a bridge using a bungee cord with stiffness k=80lb/ft. One of the men is attached to the cable and plans to release the other man when they reach the water 120ft below the bridge. Once there the connected man will let go of the unconnected man when they touch the water. Determine the unstretched length of the cord. Also determine the maximum acceleration of the attached man and the maximum height he reaches above the water when he springs back up.



Homework Equations


T1 + ƩU = T2

Us = 1/2 k (s)^2


The Attempt at a Solution



I used mgh for U and got an unstretched length of 90ft, but I'm not sure if it's correct and I don't know how to approach the kinematics of the second portion.
 
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  • #2
It helps if you show us your reasoning and not just your answer.
For the second part - why not just use conservation of energy again?
 

1. How does the length of a bungee cable affect its stretchiness?

The length of a bungee cable directly affects its stretchiness. The longer the cable, the more it will stretch when weight is added to the end. Conversely, a shorter cable will not stretch as much under the same weight.

2. What factors influence the unstretched length of a bungee cable?

The unstretched length of a bungee cable is influenced by several factors, including the material and thickness of the cable, the number of strands, and the overall construction of the bungee cord.

3. How can I determine the unstretched length of a bungee cable?

To determine the unstretched length of a bungee cable, you will need to know the weight of the object being attached to the end of the cable and the desired amount of stretch. You can then use a bungee calculator or equation to find the required unstretched length.

4. Can the unstretched length of a bungee cable be adjusted?

Yes, the unstretched length of a bungee cable can be adjusted by either changing the length of the cable itself or by adding or removing strands. However, it is important to note that altering the bungee cable may also affect its overall strength and stretchiness.

5. Why is it important to find the unstretched length of a bungee cable?

Finding the unstretched length of a bungee cable is crucial for ensuring the safety and effectiveness of bungee jumping or other activities that involve the use of bungee cords. It helps to determine the right length of the cable to achieve the desired amount of stretch, preventing accidents or injuries. Additionally, knowing the unstretched length can help with proper storage and maintenance of the bungee cable.

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