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A man walking with a speed ' v ' constant in magnitude and direction passes under a lantern hanging at
a height H above the ground (consider lantern as a point source). Find the velocity with which the edge
of the shadow of the man's head moves over the ground, if his height is ' h '.

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Velocity = H/(H-h)v

asked Jul 15, 2017 by (1.3k points) how?? plz explain it
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Assuming speed of shadow is U.

Since triangles are similar.

Speed of shadow(U)  = (V * H) / (H - h)

By similiar triangle property

(U-V)/U = h / H

So,speed of shadow (U) = (V*H)/(H-h)

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