Acceleration due to gravity - Help with equation. Thanks

[nukeman]

Homework Statement

Here is the problem:

GIven the formula below, calculate the expected value of the accerlation, G (in m/s^2). THe mass and radius of Earth are 5.974x10^24 kg and 6.37 x 10^6 m, respectively.

Formula to use: g = G Me/r^2

How do I solve for g ? I keep messing up on calculation.

Thanks

Homework Equations

The Attempt at a Solution

 

[rock.freak667]

'g' is already the subject of the formula, so you just need to substitute the numbers into the equation.

 

[nukeman]

'g' is already the subject of the formula, so you just need to substitute the numbers into the equation.

Oh. So, it would then turn into:

g = G 5.974x10^24 / 6.37 x 10^6

?

So, would the answer be? 9.378x10^29

? That can't be rigbht

 

[rock.freak667]

Oh. So, it would then turn into:

g = G 5.974x10^24 / 6.37 x 10^6

?

So, would the answer be? 9.378x10^29

? That can't be rigbht

Well 'G' is a constant such that G=6.67300 × 10^-11 m³kg^-1s^-2

And you are dividing by 10⁶,so you can't really get back 10²⁹. Redo the calculation with the value of 'G' in it.

 

[nukeman]

Well 'G' is a constant such that G=6.67300 × 10^-11 m³kg^-1s^-2

And you are dividing by 10⁶,so you can't really get back 10²⁹. Redo the calculation with the value of 'G' in it.

im real sorry, but you lost me with G

How do I do the calculation with Value G in it?

 

[rock.freak667]

im real sorry, but you lost me with G

How do I do the calculation with Value G in it?

g=GM/r²

Just replace the letters with the numbers given.

 

[nukeman]

How do I calculate this? First, is this correct?

6.6726 x 10-11N-m^2/kg^2 x 5.974x10^24 / 6.37 x 10^6

 

[rock.freak667]

How do I calculate this? First, is this correct?

6.6726 x 10-11N-m^2/kg^2 x 5.974x10^24 / 6.37 x 10^6

Your units are the same throughout, so you can leave out the units in the calculation. You also forgot to square the radius 'r'.

g= (6.67x10^-11)(5.974x10²⁴)/(6.37x10⁶)²

 

[nukeman]

I tried it 2 diferent ways.

first answer: 9.37833595 x 10^24

next: 9.8200

??

 

[rock.freak667]

next: 9.8200

This is more or less correct.

 

[nukeman]

This is more or less correct.

Is there anyway you can check, or I can be sure?

:)

 

[rock.freak667]

Is there anyway you can check, or I can be sure?

:)

Well we know that on Earth, g=9.81 m/s², so your answer should be around that number. (Depending on how accurate your values are)

 

[nukeman]

Well we know that on Earth, g=9.81 m/s², so your answer should be around that number. (Depending on how accurate your values are)

Great, good enough for me :)

Thanks VERY much for your help, really appreciate it!