### AuthorTopic: Physics Question about gravitation stuffs.  (Read 975 times)

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#### Skiffy Wolf ##### Physics Question about gravitation stuffs.
« on: February 18, 2015, 03:56:23 am »
I am actually so lost with Physics this year.
I have this questin in my book and the first one asks "In the formula v=√(GM/r), for the earh orbiting the sun, what do r and M represent?"
The answer for that is that r is the distance between the earth and the sun and M is the mass of the sun.
The second question (which is the one I'm stuck with) says "Use v=√(GM/r) to calculte the value of v."
So I know that G is 6.67*10^-11. And M is 1.99*10^30 and r is 1.49*10^11

But when I put that into the calulator my answer comes out as 3.449290124X10^24. And according to the answers the answer is supposed to be 3.0*10^4. Well how the hell does that happen? The answers don't even show working so I'm completly lost. And this is a little bit of my homeowork and it's all due on friday and I really don't think I'm gonna finish is all.

By the way throught the year I might post a lot of Phyisics questions.
« Last Edit: February 18, 2015, 04:00:02 am by Skiffy Wolf Skiffington »

#### Cookie-N ##### Re: Physics Question about gravitation stuffs.
« Reply #1 on: February 18, 2015, 05:19:03 am »
The answer of the answer is correct. By inputting it into my phone's calculator, it's 29846.7 . Usually, this happens when the calculator has the order of operations wrong (which happens a lot). Be sure to manually multiply and divide before rooting your answer instead of inputting all at once into the calculator the next time.
KEK

#### furrylifeguard ##### Re: Physics Question about gravitation stuffs.
« Reply #2 on: February 18, 2015, 08:07:50 am »
v=√(GM/r)
If you have a TI graphing calculator, try typing it into the calculator like this:

(6.67*10^-11)*(1.99*10^30)[enter]
[ans]/(1.49*10^11)[enter]
[sqrt][ans][enter]

Solve each part of the equation individually to avoid the calculator getting the order of operations mixed up. Usually that's a result of operator error when typing things in, and entering each part as a separate problem can eliminate those errors. By entering it into a graphing calculator as I wrote it above, my answer came out to 29846.7, which is fairly close to 3x10^4 (30,000).
"Do not go where the path may lead, go instead where there is no path and leave a trail." "To be yourself in a world that is constantly trying to make you something else is the greatest accomplishment." -Ralph Waldo Emerson

Feel free to talk to me! I don't bite, although I probably smell like chlorine.

#### MysticSolstice ##### Re: Physics Question about gravitation stuffs.
« Reply #3 on: February 18, 2015, 10:01:45 am »
You're steps look right, like CookieN and Furrylofegaurf said it just looks like a calculator mistake. Manually input each part in order so the order of operation is right or if your calculator has brackets on it make sure you use them to surround each part  | ToyHou.se | Twitter | Instagram |
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Thank you FT <3

#### Skiffy Wolf ##### Re: Physics Question about gravitation stuffs.
« Reply #4 on: February 19, 2015, 12:29:18 am »
Oh. Yeah so I put in each part of the equatoin sepratly and I got the correct answer.
Thanks guys!