Asked by poo
A girl of height 120 cm is walking towards a light on the ground at a speed of 0.6 m/s. Her shadow is being cast on a wall behind her that is 5 m from the light.
How is the size of her shadow changing when she is 1.5 m from the light?
How is the size of her shadow changing when she is 1.5 m from the light?
Answers
Answered by
Steve
draw a diagram. Using similar triangles, if her shadow has height h when she is x cm from the light, then
h/500 = 120/x
or,
hx = 60000
so,
h dx/dt + x dh/dt = 0
Now, find h when x = 150, and you know that dx/dt = -60 cm/s; you can then find dh/dt
h/500 = 120/x
or,
hx = 60000
so,
h dx/dt + x dh/dt = 0
Now, find h when x = 150, and you know that dx/dt = -60 cm/s; you can then find dh/dt
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.