A circular ripple in a pond is produced when a rock is dropped into the water. If the outer radius of the ripple is expanding at a rate of 24 cm/sec, at what rate is the area of the circular ripple changing when the radius is 80 cm. ?
do we know of a relation that relates these?
radius to area
you said you needed help right?
no i dnt kno the relation
Hmm, would you agree that the area of a circle is determined by the equation: pi r^2 ?
yes and the derivative of that is pi*2r
correct, except for we need to include an r' for the rate of the change of the radius
\[A = pi\ r^2\] \[A' = 2pi\ r\ r'\]
r' is told to us to be 24, and the radius = 80
A' = 2pi * 2 * 80 then
that 2 meant 24
my keyboard hates me
lol i understood what you mean ... but when i did all that i qot 12063.71579
right, cm per sec
i had that answer but it was telling me i was wrong but i had a 5 instead of 6 thnk yu sooooo much yu r qreatly appreciated
youre welcome, good luck with all of it :)
A 14 foot ladder is leaning on a wall, slowly sliding down. If the base of the ladder is sliding away from the wall at 1.3 ft/second, how fast is the top sliding vertically along the wall when the bottom of the ladder is 9 feet from the wall? do i approach it the same way ?
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