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Grade 12Mechanics

A mass m is at a distance a from one end of a uniform rod of length l and mass M. The gravitational force on the mass due to the rod is ------------

Profile image of rajan jha
15 Years agoGrade 12
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2 Answers

Profile image of vikas askiitian expert
ApprovedApproved Tutor Answer15 Years ago

force on mass m due to rod is equal to force on rod due to mass so   (action equals to reaction)

 i am calculating force on rod due to mass...

let rod is placed in x axis  such that its one end is at a distance x from origin ...mass m is placed at origin...

consider a element dx on rod at a distance x from origin...

mass of this element = dm = (M/L)dx

force on this element due to rod is dF = Gmdm/x2

           dF = Gm(M/L)dx/x2

 integrating both sides

       [F] lim0 to F = -GMm/L (1/x)          lim x to x+L

      F = GMm/x(x+L) 

approve if u like it

Profile image of Rishi Sharma
5 Years ago
Dear Student,
Please find below the solution to your problem.

force on mass m due to rod is equal to force on rod due to mass so (action equals to reaction)
i am calculating force on rod due to mass...
let rod is placed in x axis such that its one end is at a distance x from origin ...mass m is placed at origin...
consider a element dx on rod at a distance x from origin...
mass of this element = dm = (M/L)dx
force on this element due to rod is dF = Gmdm/x2
dF = Gm(M/L)dx/x2
integrating both sides
[F] lim0 to F = -GMm/L (1/x) lim x to x+L
F = GMm/x(x+L)

Thanks and Regards