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Ah, please, someone help me. I've been working on this problem for half an hour, it's the last question on my review before my test, which i want to write right now (correspondence).

If a satellite requires 2.5 h to orbit a planet with an orbital radius of 2.6 x 10^5 m, what is the mass of the planet?

ac = v^2/r = 4 pi^2 r / T^2

v = sqrt(GM / r)

(... at least that's what i think?)

1. I attempted to find the velocity from the radius (2.6*10^5) and the time (2.5hr*60*60=9000s)

v^2/r = 4 pi^2 r / T^2

v^2 = 4 pi^2 r^2 / T^2

v^2 = 4 * 3.14^2 * 2.6*10^5 / 9000^2

v=.356m/s

2. I used v= sqrt(GM/r) to find the mass.

.356= sqrt(6.67*10^-11m/2.6*10^5)

.127=6.67*10^-11m/2.6*10^5

330200=6.67*10^-11m

m= 5*10^15kg

the answer key says it's 1.3*10^20kg

## Homework Statement

If a satellite requires 2.5 h to orbit a planet with an orbital radius of 2.6 x 10^5 m, what is the mass of the planet?

## Homework Equations

ac = v^2/r = 4 pi^2 r / T^2

v = sqrt(GM / r)

(... at least that's what i think?)

## The Attempt at a Solution

1. I attempted to find the velocity from the radius (2.6*10^5) and the time (2.5hr*60*60=9000s)

v^2/r = 4 pi^2 r / T^2

v^2 = 4 pi^2 r^2 / T^2

v^2 = 4 * 3.14^2 * 2.6*10^5 / 9000^2

v=.356m/s

2. I used v= sqrt(GM/r) to find the mass.

.356= sqrt(6.67*10^-11m/2.6*10^5)

.127=6.67*10^-11m/2.6*10^5

330200=6.67*10^-11m

m= 5*10^15kg

the answer key says it's 1.3*10^20kg

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