Question

A girl of height 90 cm is walking away from the base of a lamp post at a speed of 1.2 m/sec. If the lamp post is 3.6m above the ground, find the length of her shadow after 4 seconds.

Answer 1

let shadow be s m after 4 seconds. dist trvld by girl is 4.8 m. we have two similar rt ld ∆s base s height 0.9 and base (s+4.8) height 3.6. by ratio prop s/0.9=(s+4.8)/3.6. solution is s=1.6 m