Question

Can someone please help me with this

Answer 1

Area enclosed by ripple, A = \(\pi r^2\) -------- (1)

rate of change of A, dA/dt = 2.pi.r. dr/dt
= 2.pi.r.4
= 8.pi.r -----------------(2)

Answer 2

ok

Answer 3

its Given : after 10 seconds, dA/dt = k.pi

Answer 4

k=8

Answer 5

so, at 10 seconds :-

dA/dt = 8.pi.r = k.pi
=>
k = 8.r

Answer 6

what is the r

Answer 7

good q,

since r is changing at 4 ft/s, at 10th second r = 4*10 = 40

so k = 8.r = 8 * 40 = ?

Answer 8

320

Answer 9

os then the 320 is my final answer correct?

Answer 10

yep !

Answer 11

ok thanks

Answer 12

np