PHY Gravity

Accoding to Newton's Law of Gravitation, the force of attraction F on an object (of mass m) by the earth (of mass M) is given by,

F = GMm/R^2
where G is the Universal Gravitational Constant.
R is the distance of the object from the earth centre

Since the weight of the object = mg, where g is the acceleration due to gravity
hence, mg = GMm/R^2
i.e. g = GM/R^2

When the object is at the top of a mountain, its distance from the earth centre is larger than that on earth surface (sea level), since g is inversely proportional from the square of distance (see equation above), the value of g on mountain top is thus smaller than that at sea level.

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