Question

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Answer 1

can you differentiate S with respect to r ?

Answer 2

to find dS/dr first ?

Answer 3

actually pretty entirely lost on this and need someone to walk me through it if possible!

Answer 4

do you know whats d/dx (x^2) =.. ?

Answer 5

d(x^2)/dx(x^2) or no

Answer 6

i was just asking what derivative of x^2 is .... ?

Answer 7

d/dx?

Answer 8

did you solve any derivative problem before ?

Answer 9

you asked the derivative of x^2..so d/dx(x^2) no?

Answer 10

which equals ?

Answer 11

2x

Answer 12

yes
do d/dr r^2 = 2r

now can you find dS/dr ?

Answer 13

confused on the inputs here, do i just use the 4pi r^2 / ?

Answer 14

dS /dr = 4pi d/dr (r^2) = 4pi (2r) = 8 pi r
got this ?

Answer 15

roughly yeah

Answer 16

so
dS - 8pi r dr
just divide both sides by dt now...

Answer 17

dS = 8pi r dr

Answer 18

so you did d/dx -> 2x, d/dr -> 2r, and ds/dr-> 8pi r, how do we establish the dt is what I'm lost with now for the division

Answer 19

just divide both sides by dt....

Answer 20

dS/dt = 8 pi r dr/dt
thats it!

Answer 21

thats it?

Answer 22

just add in the dt?

Answer 23

*divide both sides by dt
ys

Answer 24

so just ds=8 pi r dr

Answer 25

"Write an equation that relates dS/dt to dr/dt ."
dS/dt = 8 pi r dr/dt
thats it!

Answer 26

ok thanks, sorry all the relations are somewhat confusing to me, thanks tho

Answer 27

no problem,
welcome :)