kinematics question1:

Question

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 '.

Answer 1

Velocity = H/(H-h)v

Answer 2

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)