Physics help from experts.
In classical physics ("mechanics"), gravity is an attracting force between two objects having mass. Gravitational field intensity (gravitational field strength) is the amount of force exerted on each unit of mass of an object at a point in space caused by the presence of another object. "Space" includes a region on or near the surface of a planet. The more massive object is usually considered the source of the field. Gravitational field intensity has the units N/kg and is a vector that points to the source's centre of mass. g = GM/R2 where
G = 6.67 x 10-11 Nm2/kg2
M is mass in kg of the source
R is the separation in m between the center of mass of the source and the point in space
Imagine a planet started shrinking without any change in mass. Once the planet reached one-half its original diameter, the weight of objects on its surface would be
a. half their original weight.
b. the same weight as their original weight.
c. twice their original weight.
d. four times their original weight.