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n1. Ifg is the acceleration due to gravity on thesurface of the earth, the gain in potentialenergy of an object of mass in raised fromthe earth's surface to a height equal to theradius Ro the earth is

Answer»

Let

R→Radius of the earth

M→Mass of the earth

m→Mass of the body

g→Acceleration due to gravity on earthWhen the body is on earth surface, considering the force of attraction of earth on it we can write

mg = GMm/R^2 where G = Gravitational constant

⇒GM = gR^2.....(1)

Now the PE of the system when the body is on the surface

Es = −GmMR....(2)

Again the PE of the system when the body is at height h from the the earth surface is given by

Eh = −GmM/R+h

If h = R then

ER = −GmM/R+R = −GmM/2R....(3)

Soincrease in PEdue to shift of the body of massmfrom surface to the height equal to the radius (R) of the earth is given by:

ΔEp = ER−Es = −GmM/2R + GmM/R = GmM/2R = mgR^2/2R = 1/2mgR

Inserting GM = gR^2 from (1)



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