Is This Calculator Incorrect for Predicting Impact Force of a Falling Object?

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Homework Help Overview

The discussion revolves around the accuracy of a calculator used to predict the impact force of a falling object, specifically examining the assumptions made regarding forces acting on the object during its fall and upon impact.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the assumptions behind the calculator's methodology, particularly regarding the inclusion of gravitational forces and stopping distances in the calculations. Questions are raised about the interpretation of the height and stopping distance in the context of the impact force calculation.

Discussion Status

Some participants have provided insights into the implications of the calculator's assumptions, suggesting that the height should account for the stopping distance. There is acknowledgment of differing interpretations regarding the disclaimer provided on the calculator's page, indicating an ongoing exploration of the topic.

Contextual Notes

Participants note that the accuracy of the impact force calculation may depend on whether the stopping distance is considered in relation to the total height of the fall. There is mention of specific example values used in the discussion, which may not fully represent the general case.

westerndragon76
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I believe that this calculator generates answers assuming that the only force acting on a falling object after it has encountered a stopping surface is the force of the stopping surface. The calculator needs to factor in gravity throughout the whole fall. Would someone else please verify?
http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
Click Mechanics, work-energy principle, and then impact force of falling object, and "Since you know velocity, mass, and kinetic energy, can you predict the force of impact?"
Example numbers:
m=50kg, h=10m, d=5m
stopping force should be about 1480N, but the calculator is saying 980N.
 
Last edited:
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Read the little note at the bottom of that page.

Note that the above calculation of impact force is accurate only if the height h includes the stopping distance, since the process of penetration is further decreasing its gravitational potential energy.

That should take care of your problem (you probably should use d=5, h=5 to describe the situation I think you have in mind). If not for this disclaimer, the calculation would be, as you point out, wrong for the general case where d is not necessarily small compared to h.
 
I didn't take time to read that disclaimer carefully. Thanks for the quick answer!
 
It is not a disclaimer, it is a caveat. :mad:
 

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