How Much Energy is Absorbed Elastically When a Person Lands on Their Feet?

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Homework Help Overview

The discussion revolves around the energy absorption of a person landing on their feet, specifically focusing on the elastic energy stored in the Achilles tendon and other factors involved in the landing process. The subject area includes concepts from mechanics and energy transfer.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the energy absorption during landing, questioning how to calculate the energy stored in the Achilles tendon treated as a spring. There are attempts to determine the spring constant and the total energy just before impact.

Discussion Status

The discussion is ongoing, with participants expressing confusion about the calculations involved. Some guidance is offered regarding determining the energy of the person before landing and the spring constant of the tendons, but no consensus has been reached.

Contextual Notes

Key assumptions regarding the mechanics of landing and the properties of the Achilles tendon are under discussion, including the maximum force and extension of the tendon. Participants are also navigating the constraints of the problem as presented.

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Homework Statement


A 60 kg person lands on their 2 feet on a floor with a speed of 3.5 m/s.?
Energy dispatched in a variety of ways, including compression in the cartilage of your knees, in the soles of your shoes etc. calf and thigh muscles have a major role. elastic stretching of your Achilles tendon also plays a part.
a) if the extension of the tendon is 0.010m and is the maximum force (in one tendon) is 1800 N, how much energy is absorbed elastically? state any key assumption made.
b) what fraction of the energy just prior to impact is absorbed in this way?

Homework Equations


I'm so confused I have no idea :(


The Attempt at a Solution

 
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debzrie said:

Homework Statement


A 60 kg person lands on their 2 feet on a floor with a speed of 3.5 m/s.?
Energy dispatched in a variety of ways, including compression in the cartilage of your knees, in the soles of your shoes etc. calf and thigh muscles have a major role. elastic stretching of your Achilles tendon also plays a part.
a) if the extension of the tendon is 0.010m and is the maximum force (in one tendon) is 1800 N, how much energy is absorbed elastically? state any key assumption made.
b) what fraction of the energy just prior to impact is absorbed in this way?
Think of the tendon as a spring that is stretched from 0 to .01 m in stopping the fall. What is the spring constant k of that spring? How much energy is stored in that spring when stretched to .01 m? How much energy does the person have just before landing? How much of that energy can be stored in those tendon springs?

AM
 
still a little confused :S
 
debzrie said:
still a little confused :S
What are you confused about?

Can you determine the energy of the person just before landing? Can you determine the spring constant of the tendons?

AM
 
Last edited:

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