What Is the Net Force on the Moon During Eclipses?

AI Thread Summary
The discussion focuses on calculating the net gravitational force on the Moon during solar and lunar eclipses using given masses and distances. The gravitational force formula Fg=G x M1 x M2/D^2 is applied, with the correct lineups for solar (Sun-Moon-Earth) and lunar (Sun-Earth-Moon) eclipses noted. An attempt to calculate the net force resulted in an incorrect answer, prompting questions about the distance values used and the potential need to account for additional forces. Participants encourage sharing detailed math steps for better verification. The conversation emphasizes the importance of accuracy in distance measurements and significant figures in calculations.
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Homework Statement


mass of star = 2.53 x 1030 kilograms
mass of planet = 5.25 x 1024 kilograms
mass of moon = 8.09 x 1022 kilograms
average distance from star to planet = 1.14 x 1011 meters
average distance from planet to moon = 4.59 x 108 meters

Use the data above to determine the net force exerted on the moon by the planet and the star during:
a. a solar eclipse.
WebAssign will check your answer for the correct number of significant figures. wrong check mark N
b. a lunar eclipse.
WebAssign will check your answer for the correct number of significant figures. wrong check mark N


Homework Equations


Fg=G x M1 x M2/Dsquared
Note that the lineup for a solar eclipse is Sun-Moon-Earth
A lunar eclipse lineup is Sun-Earth-Moon
This I am sure of.

The Attempt at a Solution


My attempt was to find the netforce of gravity on the moon.
Here is my work which produced a wrong answer.
a) Fgrav,net=Gm(moon)M(sun)/Dsquared(the distance between the star and the planet- the distance between the planet and the moon) - GM(moon)M(earth)/dsquared
Perhaps I added the distances wrong- but I know when the moon is in the middle I will have opposite signs for the forces from each planet and the lunar eclipse should produce. I got 9.18E20 rounded for my answer to part a. Any ideas? Am i using the distance wrong? Any similar answers? Any other forces to be accounted for in the net sum? Thanks.
 
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It looks like you are using the correct approach. Can you write out your math steps to make it easier to check them?
 

Thread 'Errors and significant figures'

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...
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Thread 'A cylinder connected to a hanging mass'

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...
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