- #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.

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- Thread starter shanshan
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- #1

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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?

I have nothing.

- #2

cronxeh

Gold Member

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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

Keeping in mind that you are given dB/dt and asked to find dA/dt

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- #3

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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

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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

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ahhhh and the light goes on. thankyou!

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