Gravitational force and constants

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Homework Help Overview

The problem involves calculating the net gravitational force on a mass located at the origin due to two other identical masses positioned along the x-axis. The gravitational constant is provided, and the masses are specified as 570 kg each, with their respective positions given in centimeters.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the calculation of gravitational forces using the formula F=G(m1m2/R^2) and express confusion about the direction of the forces involved. There are attempts to clarify the vector nature of the forces and the need for proper sign conventions in the calculations.

Discussion Status

The discussion is ongoing, with participants exploring the implications of force direction and the potential for small numerical results to be misinterpreted as zero. Some guidance has been offered regarding the correct approach to vector subtraction and the interpretation of the forces acting on the mass at the origin.

Contextual Notes

There is a mention of the answer being very small, leading to confusion about whether it could be considered zero. Participants are questioning the assumptions made in the calculations and the setup of the problem.

juggalomike
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Homework Statement


Three identical masses of 570 kg each are placed on the x axis. One mass is at x_1 = -10.0 cm, one is at the origin, and one is at x_2 = 43.0 cm.

What is the magnitude of the net gravitational force F_grav on the mass at the origin due to the other two masses?

Take the gravitational constant to be G = 6.67×10−11 N * m^2/kg^2.


Homework Equations



F=G(m1m2/R^2)

F=F1-F2

The Attempt at a Solution



-(6.67*10^-11)*(570^2)/(-.1)^2 - (6.67*10^-11)*(570^2)/(.43)^2 =-0023 N

What am i doing wrong?
 
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maybe you want to reconsider the direction of each force .. (you should do vector subtraction) ..
 
thebigstar25 said:
maybe you want to reconsider the direction of each force .. (you should do vector subtraction) ..

tried it, still telling me the answer is not 0...
 
why should the answer be zero?
 
thebigstar25 said:
why should the answer be zero?

The answer is not zero, however because my number is so small it is considering it to be 0
 
juggalomike said:

Homework Statement


Three identical masses of 570 kg each are placed on the x axis. One mass is at x_1 = -10.0 cm, one is at the origin, and one is at x_2 = 43.0 cm.

What is the magnitude of the net gravitational force F_grav on the mass at the origin due to the other two masses?

Take the gravitational constant to be G = 6.67×10−11 N * m^2/kg^2.


Homework Equations



F=G(m1m2/R^2)

F=F1-F2

The Attempt at a Solution



-(6.67*10^-11)*(570^2)/(-.1)^2 - (6.67*10^-11)*(570^2)/(.43)^2 =-0023 N

What am i doing wrong?

The answer is small. But in the expression you gave you are adding both forces in the negative direction. The sign should be different between them. One should be pulling in the positive direction and the other in the negative. I think this was thebigstar25's point.
 
thanks Dick for explaning my point in a better way .. I think now juggalomike can solve the problem ..
 

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