# Calculating Altitude (1 Viewer)

#### -tal-

##### Member
I've been sitting here for 15 minutes trying to plonk in numbers and they're making no sense to me.

#### nwong6

##### New Member
$\bg_white f = ma ,a = f/m ,0.233ms^-2 = f/540 kg ,f = 125.82 Nm ,f = (Gm1m2)/ r^2 ,f = (6.7*10^-11)(5.98*10^24)(540)/((6.38*10^6)+ X)^2 ,125.82 Nm = (6.7*10^-11)(5.98*10^24)(540)/((6.38*10^6)+ X)^2 ,(6.7*10^-11)(5.98*10^24)(540)/125.82 Nm = ((6.38*10^6)+ X)^2 , 41467708.1 =(6.38*10^6)+ X)= r$

im really bad at physics lol. i have no idea how to use the thingo above either.

f = ma

a = f/m

0.233ms^-2 = f/540 kg

f = 125.82 Nm

f = (Gm1m2)/ r^2

f = (6.7*10^-11)(5.98*10^24)(540)/((6.38*10^6)+ X)^2

125.82 Nm = (6.7*10^-11)(5.98*10^24)(540)/((6.38*10^6)+ X)^2

(6.7*10^-11)(5.98*10^24)(540)/125.82 Nm = ((6.38*10^6)+ X)^2

41467708.1 =(6.38*10^6)+ X)= r

:. r = 4.1*10^7m

EDIT:

41467708.1 - (6.38*10^6) = X

X = 35,087,708.1 m = 35,087.7 km = 3.50 x 10^4 km

Last edited:

#### darkchild69

##### Nanotechnologist
Ha ha, this one's on the house again tal, it's somewhat similar to that other problem.

g = Gm / r^2

r = *sqroot Gm / g

= *sqroot (6.67 x 10^-11) x (5.98 x 10^24) / 0.233

= 4.14 x 10^7

But then you have to remember that the Earth's radius is 6.38 x 10^6, and so you have to minus this amount to get the altitude. That should give you exactly 3.50 x 10^7 or (D)

The answer is (c), not (d) as you have to convert from metres to kilometres!