Question

Find the depth at which the G-field of a star is 25% with a density given by p(x), given radius is 4000km and mass at the surface is 3000kg.

Answer 1

@UnkleRhaukus

Answer 2

p=m/v

now i know that the change in density is going to be due to the change i mass and volume

Answer 3

so would it be

\[dp=\frac{dm}{dv}\]

Answer 4

my teacher had his second equation in a similar problem as

\[pdv=dm\]

which i can only get if i let

\[p*dv=\frac{dm}{dv}*dv\]

Answer 5

p is a linear function also

Answer 6

What subject is this?

Answer 7

it's calculus-based physics

Answer 8

the only unrelevant equation that makes it physics is

\[g=\frac{Gm}{r^2}\] where G is the gravitational constant \[6.67*10^{-11}\]
m is the mass below and r is the radius to the center

Answer 9

so since we're given a radius and a mass you can find out what the Gfield is at the surface and solve for what 25% of it is. However to find the unknowns depth and mass , we need calculus

Answer 10

calculus is needed due to the fact that the mass and volume are changing as you get farther into the core which changes the density

Answer 11

\[dp \neq \frac{ dm }{ dv }\]

Answer 12

\[p=\frac{dm}{dv}\]

Answer 13

\[dp = \frac{ vdm - mdv }{ v^2 }\]

Answer 14

correct so where does \[pdv=dm\] come from

Answer 15

by any chance, is the density function given? p(x)?

Answer 16

ehh i think it was something like (-.0000007+10^4)r

Answer 17

it is (-.000005r+10^4)

Answer 18

So p(x) is (-.000005r+10^4)?

Answer 19

pdv = dm is wrong

Answer 20

p(x) given?

Answer 21

p=-.0000004r+10^4

Answer 22

i need somehow to relate the change of mass nad volume to the change in radius

Answer 23

or change in density