Hey, I am having a really hard time solving this problem. I need all the help you can give me.
When a small pebble is dropped in a pool of still water, it produces a circular wave that travels outward at a constant speed of 15 cm/s. At what rate is the area inside the wave increasing
a) when the radius is 5 cm?
b) when the area is 400pi cm^2
c) when 4s have elapsed
Basically I have no idea how to solve this problem. I know that the area of a circle can be found by . However I do not know how to factor in the fact that the wave is traveling at 15m/s.
Any help is greatly appreciated!
I went to move onto the next problem, but it is similar. I need help understanding how to answer these. Here is next question:
The angle of elevation of the sun is decreasing at 1/4 rad/h. How fast is the shadow cast by a building of height 50m lengthening, when the angle of elevation of the sun is pi/4?
I am having the same problem. I do not know how to go about solving this.