Question

Guys i really need help w/ this question! keep getting it wrong.

A 203.7-kg satellite is orbiting planet Y at an altitude of 1.3x10^6 meters above its surface and with an orbital period of 19.4 hours. If the planet has a mass of 1.9x10^24 kg, then determine the radius of planet Y.

Answer 1

Hmmm this seems like a problem with Kepler's third law.
I can solve it for you.

Answer 2

You need to determine the radius of orbit. (The mass of the satellite doesn't matter).
radius = cube root (G * mass * t^2 / 4 * PI^2)
G= 6.67*10-11
mass is in kilograms
t must be in seconds

Answer 3

is the mass required for that formula of the planet or of the sattelite?

Answer 4

Mass of the planet. The 203.7 kg satellite mass isn't needed.

Answer 5

ok, my radius is 115131988.661

Answer 6

Mass is 1.9 x 10^24 kg
We need time in seconds so
19.4 hours * 3,600=
69,840

Answer 7

How did you get that radius - I have a different answer
25,017,000 meters

Answer 8

i probabliy made a mistake in the algebra.

Answer 9

Did you use my formula or some other one?

Answer 10

i used yours

Answer 11

i checked the answer and its wrong please help me dude

Answer 12

Is 25,017,000 meters correct?

Answer 13

the answer has to be in ___e7 where do i put the decimal?

Answer 14

2.5017 e 7

Answer 15

Which is 2.5017x 10 ^7

Answer 16

i entered that, but it is incorrect

Answer 17

Okay round it off to 2.5e7

Answer 18

incorrecto

Answer 19

I tried my calculator on my website: http://www.1728.org/kepler3a.htm
and it calculates 2.5e7
Does your answer have to be in meters?

Answer 20

it does have to be in meters

Answer 21

tyring to find the radius of the planet in meters

Answer 22

*trying

Answer 23

Well my answer is 25,000,000 meters.
I'm pretty sure that is it. (I wrote that calculator)

Answer 24

idk how but its incorrect, thanks for your time tho

Answer 25

I'm willing to work on this a bit more though.

Answer 26

how do we find radius of the planet, not raidus of the orbit

Answer 27

Oh geez - the planet!!!!!!!!!!!
The satellite is orbitting at 1,300,000 meters above the surface
So, subtract 1,300,000 from 25,000,000

Answer 28

That should be 23,700,000

Answer 29

It's right! thanks a lot dude life saver for sure

Answer 30

Okay if you need help with those Kepler 3rd law problems, go to that link
Or see the rest of my website
http://www.1728.org