Related rates question, shadow

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Homework Help Overview

The problem involves related rates in the context of geometry, specifically using similar triangles to analyze the relationship between a man's distance from a light source and the length of his shadow as he walks away.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss using similar triangles to establish a relationship between the shadow length and the distance from the light source. Questions arise regarding the adequacy of the given dimensions for applying this method.

Discussion Status

Some participants have suggested a method involving similar triangles, while others are questioning the application of this approach due to the dimensions provided. There appears to be a moment of realization from one participant, indicating a potential breakthrough in understanding the relationship.

Contextual Notes

The original poster has not provided any initial attempts or equations, indicating a lack of starting information. The discussion includes a visual aid to clarify the geometric relationships involved.

shanshan
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Homework Statement


A man 6m tall walks away from a light 10m above the ground. If his shadow lengthens at a rate of 2m/s, how fast is he walking?


Homework Equations





The Attempt at a Solution


I have nothing.
 
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Using similar triangles you can find the relationship between the shadow length (B) and distance away from pole (A).


Keeping in mind that you are given dB/dt and asked to find dA/dt
 
Last edited:
but how can i use similar triangles if i only have one of the dimensions of the triangle?
 
shanshan said:
but how can i use similar triangles if i only have one of the dimensions of the triangle?

Look at the picture I attached. The relationship between ratios is constant, therefore the relationship between speed of man and length of shadow is constant
 
ahhhh and the light goes on. thankyou!
 

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