Acceleration due to gravity
The acceleration for any object moving under the sole influence of gravity is known as acceleration due to gravity. So, for an object of mass `m,` the acceleration experienced by it is usually denoted by the symbol g which is related to F by Newton’s second law by relation `F= mg`. Thus,
`g=F/m=(GM_e)/(r_e^2)`
Acceleration `g` is readily measurable as `R_e` is a known quantity. The measurement of `G` by Cavendish’s experiment (or otherwise), combined with knowledge of `g and R_e` enables one to estimate `M_e` from the above equation. This is the reason why there is a popular statement regarding Cavendish “Cavendish weighed the earth”. The value of `g` decrease as we go upwards from the earth’s surface or downwards, but it is maximum at its surface
If `g` is the acceleration due to gravity at the surface of the earth, the force acting on the particle of mass `m` placed at the surface is
Options:
(a) `mg`
(b) `(GmM_e)/(R_e^2)`
(c) Data insufficient
(d) Both ( a) and ( b)