How fast does the Earth need to move to provide centripital acceleration

[Sabalaba]

How did u do c,d and e??

 

[hefalomp]

For e you know that (G*M*m)/r^2 is the force and since F=m*a where a=v^2/r you can solve the problem by solving it for v and then setting in the formula for T instead. Then you will get the time for one lap. If you are a UiS student and that's why you're wondering about d I would suggest you ask the student helpers this week. They can probably explain it way better than me since writing step by step here would take a long time for me

Did you get the periode for the object to do one lap equal to 268,7s ?? Felt that this answear was very small, but i got the formula T = 2*pi*r / (sqrt(G*M/r)

 

[Makonia]

Did you get the periode for the object to do one lap equal to 268,7s ?? Felt that this answear was very small, but i got the formula T = 2*pi*r / (sqrt(G*M/r)

No I got 6000 and something s, your formula looks wrong so you should try to do it again

 

[Makonia]

How did u do c,d and e??

How to do both c and e is written in this thread so just read it. For d it's difficult for me to explain because I'm not sure myself. Thats why I asked here but don't know if I'm all that wiser on it anyways

 

[Sabalaba]

How to do both c and e is written in this thread so just read it. For d it's difficult for me to explain because I'm not sure myself. Thats why I asked here but don't know if I'm all that wiser on it anyways

ok, thank u!
The problems are so hard

 

[hefalomp]

No I got 6000 and something s, your formula looks wrong so you should try to do it again

I think i figured it out, i used wrong radius, i forgot to add up the radius of the Earth as well :s, i now got 6170 s, is that the same as u got?

 

[Makonia]

I think i figured it out, i used wrong radius, i forgot to add up the radius of the Earth as well :s, i now got 6170 s, is that the same as u got?

No, I got a little bit more. You used this equation: T = 2*pi*r / (sqrt(G*M/r)?

 

[hefalomp]

Yes, might be that that is wrong then? But you said that (G*M*m)/r^2 is the force and since F=m*a where a=v^2/r you can solve the problem by solving it for v and then setting in the formula for T instead. Can i not use that (G*M*m)/r^2 = m* v^2/r, and solv it for v, then put v in T = 2*pi*r/v ?

 

[Makonia]

Yes, might be that that is wrong then? But you said that (G*M*m)/r^2 is the force and since F=m*a where a=v^2/r you can solve the problem by solving it for v and then setting in the formula for T instead. Can i not use that (G*M*m)/r^2 = m* v^2/r, and solv it for v, then put v in T = 2*pi*r/v ?

I guess we have just done it differently. I got the formula: T=sqrt((4*pi^2*r^3)/(G*M))

 

[jensjensen]

You have used the same formula. One formula is just simplified

 

[hefalomp]

I guess we have just done it differently. I got the formula: T=sqrt((4*pi^2*r^3)/(G*M))

Even when I use your formula i also get 6170 seconds, do you use r = 7271000 , M = 5,97219*10^24 and G = 6.67408*10^-11 ?

 

[jensjensen]

r is 7,3*10^6

 

[Makonia]

Even when I use your formula i also get 6170 seconds, do you use r = 7271000 , M = 5,97219*10^24 and G = 6.67408*10^-11 ?

No I use the values for r, M and g stated in the task. In other words M=6*10^24, r = 7300*10^3 and I used G with two decimals

 

[hefalomp]

No I use the values for r, M and g stated in the task. In other words M=6*10^24, r = 7300*10^3 and I used G with two decimals

Well, that's explanes why i got wrong, i searched for the radius and mass of Earth on google, didnt se that they were mentioned in the task :) Now i should get the right answear..