Gm1m2 / d2 = kq1q2 / d2What is the value of Q to maintain the present orbit?

  • Thread starter Thread starter Littlemin5
  • Start date Start date
  • Tags Tags
    Earth Moon
AI Thread Summary
The discussion centers on calculating the charge value Q needed for electrical attraction to maintain the Moon's orbit around the Earth, instead of gravitational force. The relevant equations for gravitational force (Fg) and electrical force (Fe) are provided, along with the masses of the Earth and Moon and the radius of their orbit. The user expresses uncertainty on how to proceed after calculating the gravitational force. It is noted that if the orbit remains unchanged, the acceleration must also remain constant, implying that the forces must be equal. The thread seeks assistance in solving this physics problem.
Littlemin5
Messages
15
Reaction score
0

Homework Statement



Supppose that electrical attraction, rather than gravity were responsible for holding the moon in orbit around the earth. If equal and opposite charges Q were placed on the Earth and the Moon, What should be the value of Q to maintain the present orbit?

Treat the Earth and Moon as point particles

Homework Equations



Mass of earth: 5.97x1024kg
Mass of moon: 7.35x1022kg
radius of orbit: 3.84x108m

Fg=Gm1m2 / d2
Fe= kq1q2 / d2

The Attempt at a Solution



Well I know to start by finding the force of gravity, but from there i am unsure about how to do this problem. Could someone please help?
 
Physics news on Phys.org
If the orbit remains the same, then so does the acceleration.
Since the masses are the same, so are the forces: Fg=Fq
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top