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

Answer:

The velocity will be Hv/H-l v

Explanation:

Let a triangle named PQR and within this another PST

Let QR=a and ST= b PQ= L SQ=l

and, ST/PS= QR/PQ

    => b/L-l= a/L

we know that

b= vt

now by putting the value of b,

=> vt/L-l=  a/L

Now, the let the velocity is V,

Therefore,

V= Lv/L-l

or V= Hv/H-l