Question

Question #fe069

Answer 1

The rate of change of the length of the shadow would be a constant = 5.6 ft per second

Explanation:

Let the length of the shadow at any time t secs after woman walks away from the wall be x ft. During this time she would have walked away 4t feet from the wall, as shown in the figure.

The height of the woman 5ft 10 inches would be `35/6 ft`
Comparing two similar triangles, as seen in the figure, it would be `x/(35/6)= (x+4t)/10` `-> (6x)/35= (x+4t)/10`. On simplification it would be 25x= 140t. Differentiating w.r.t t, `dx/dt= 140/25=28/5=`5.6ft/sec