Mathematics

Problem

A floodlight

12\,\text{m}

above level ground is located

15\,\text{m}

in front of a vertical wall. A

1.8\,\text{m}

-tall worker walks directly toward the wall, starting from the floodlight, at a speed of

1.2\,\text{m/s}

. When the worker is

10\,\text{m}

from the base of the floodlight, how fast (in

\text{m/s}

) is the top of the worker’s shadow moving upward along the wall? (Positive values indicate upward motion.) a)

1.53

1.84

-1.84

0.82