A straight rod of length extends from to

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A straight rod of length LL extends from x=ax = a to x=L+ax = L + a. The gravitational force exerted by it on a point mass mm at x=0x = 0, if the linear density of rod is μ=A+Bx2\mu = A + Bx^2 (where xx is the xx-coordinate) is: (A) Gm[Aa+BL]Gm \left[ \frac{A}{a} + BL \right] (B) Gm[A(1a−1a+L)+BL]Gm \left[ A \left( \frac{1}{a} - \frac{1}{a+L} \right) + BL \right] (C) Gm[BL+Aa+L]Gm \left[ BL + \frac{A}{a+L} \right] (D) Gm[BL−Aa]Gm \left[ BL - \frac{A}{a} \right]

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