Two heavy spheres, each of mass 100kg and radius 0.8 m are placed 1m about on a table What is the gravitational force and potential at the mid point of the line joining the centres of the spheres ?

Explanation

A & B be the two given spheres & O = mid point
If `E_(1) & E_(2)` are the gravitaitonal fields
`E_(1) = (G xx 100)/((0.5)^(2)) , E_(2) = (G xx 100)/((0.5)^2)`
`E_(1) & E_(2)` are equal & opposite, then resultant gravitational field at O is zero.
V - gravitational potential at O due to A & B
`V = - (G.100)/(0.5) - (G.100)/(0.5) = - (2G.100)/(0.5)`
` = (-200 xx 6.67 xx 10^(-11))/(0.5) = -2.7 xx 10^(-8) J//kg`.