Question

Page No:
Date.
A stone is dropped into a pond.
Waves in the form & circles are
generated and the radius of the outermost
ripple increases at the rate of
2 inches per second. How fast is the area increasing
when
(12 the rading is 5 inches?
(1) after 5 seconds?​

Answer 1

Answer:

1) 20π

2)40π

Step-by-step explanation:

a/c dr/dt = 2inches/sec.....(1)

i) r= 5inches

A= πr^2

differentiating b.s

dA/dt=π2r.dr/dt

=2*π*2*5

=20π

ii)if dr/dt=2inches/sec

then after time t 'r' would be 2*t inches

i.e r=2*5=10inches

therefore, dA/dt=2*π*10*2

=40π

hope it helps..

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