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Related rates question, shadow

  • Thread starter shanshan
  • Start date
  • #1
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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.
 

Answers and Replies

  • #2
cronxeh
Gold Member
961
10
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:
  • #3
24
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but how can i use similar triangles if i only have one of the dimensions of the triangle?
 
  • #4
cronxeh
Gold Member
961
10
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
 
  • #5
24
0
ahhhh and the light goes on. thankyou!
 

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