The Walking Girl & The Shadow

An interactive physics problem based on similar triangles.

The Problem

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

Adjust the Variables

Lamp-post Height 3.60 m

Girl's Height 0.90 m

Girl's Speed 1.20 m/s

Time Elapsed 4.0 s

A

B

C

D

E

Solution Breakdown

Length of the Shadow (DE):

1.60 m