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QJEEM19Phc334: JEE Main 2019 Physics - Class 11 JEEM19Phc334 Solution: A straight rod of length L extends from x = a to x = L + a. The …

A straight rod of length L extends from x = a to x = L + a. The gravitational force it exerts on a point mass 'm' at x = 0, if the mass per unit length of the rod is A + Bx2 , is given by :

Multiple Choice Options

  • A Gm[A(1a−1a+L)−BL]
  • B Gm[A(1a−1a+L)+BL]
  • C Gm[A(1a+L−1a)+BL]
  • D Gm[A(1a+L−1a)−BL]

Step-by-Step Verified Solution

JEE Main 2019 (Online) 12th January Morning Slot Physics - Gravitation Question 156 English Explanation
dm = (A + Bx2)dx

dF = GMdmx2

F = ∫aa+LGMx2 (A + Bx2)dx

= GM[−Ax+Bx]aa+L

= GM[A(1a−1a+L)+BL]

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