- #26

- 12,121

- 159

You're not far off. Something went awry when you plugged in the numbers, but you are close.

- Thread starter tascja
- Start date

- #26

- 12,121

- 159

You're not far off. Something went awry when you plugged in the numbers, but you are close.

- #27

- 87

- 0

mE: 5.98x10^24 kg

mM: 7.35x10^22 kg

R: 3.84x10^8 m

= 2(5.98x10^24)(3.84x10^8) +/- { 4(7.35x10^22)(5.98x10^24)(3.84x10^8)} /

2(5.98x10^24) - 2(7.35x10^22)

= 4.6x10^33 +/- {6.8x10^56} / 1.2x10^25

= 4.6x10^33 / 1.2x10^25

= 3.8x10^8

**i rounded the numbers i wrote here just to write less, but i plugged in complete numbers into the calculator

- #28

- 87

- 0

dE = {mE}(R) / {mM}+{mE}

= 3.457x10^8 m

** which sounds more reasonable as an answer

- #29

- 454

- 0

According to your equation dE = 3.79*10^8 wich is much too close to the moon.

dE = {mE}(R) / {mM}+{mE}

= 3.457x10^8 m

** which sounds more reasonable as an answer

[tex]\frac {2 m_e R \pm \sqrt {4 m_e m_m R^2}} { 2m_e - 2m_m} [/tex]

this is really correct. You can still cancel a 2 and get R^2 out from under the square root sign. I hope you do not do the algebra in ascii, but write it out on paper.

A calculator that does variables is very useful. It's much harder to make mistakes if

you can enter:

>>> me = 5.98e24

>>> mm = 7.35e22

>>> R = 3.84e8

>>> me*R/(mm+me)

379337573.30469972

(this is in python)

- #30

- 12,121

- 159

Here you forgot to square R inside the square root { } expression. It should be= 2(5.98x10^24)(3.84x10^8) +/- { 4(7.35x10^22)(5.98x10^24)(3.84x10^8)} /

2(5.98x10^24) - 2(7.35x10^22)

= 4.6x10^33 +/- {6.8x10^56} / 1.2x10^25

(3.84x10^8)

Anyway, you got it to work out (perhaps by reading the other thread with this same problem).

p.s. Note to kammerling: he is using { } to signify square rooots.

Last edited:

- Last Post

- Replies
- 17

- Views
- 4K

- Last Post

- Replies
- 3

- Views
- 4K

- Last Post

- Replies
- 5

- Views
- 3K

- Replies
- 4

- Views
- 2K

- Last Post

- Replies
- 6

- Views
- 11K

- Last Post

- Replies
- 19

- Views
- 2K

- Last Post

- Replies
- 2

- Views
- 2K

- Last Post

- Replies
- 1

- Views
- 1K

- Last Post

- Replies
- 0

- Views
- 2K

- Replies
- 1

- Views
- 5K