Gravitation Question 125

Question: The masses and radii of the earth and moon are [M1,,R1] and [M2,,R2] respectively. Their centres are distance d apart. The minimum velocity with which a particle of mass m should be projected from a point midway between their centres so that it escapes to infinity is [MP PET 1997]

Options:

A) [2Gd(M1+M2)]

B) [22Gd(M1+M2)]

C) [2Gmd(M1+M2)]

D) [2Gm(M1+M2)d(R1+R2)]

Show Answer

Answer:

Correct Answer: A

Solution:

Gravitational potential at mid point [V=GM1d/2+GM2d/2] Now, [PE=m×V=2Gmd(M1+M2)] [m = mass of particle] So, for projecting particle from mid point to infinity [KE,=,|,PE,|] [,12mv2=2,Gmd(M1+M2)] [,v=2G,(M1+M2)d]



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