On the surface of the earth, weight is calculated by multiplying mass
and gravity.
Because we know the radius of the Earth, we can use the Law of
Universal Gravitation to calculate the mass of the Earth in terms of the
gravitational force on an object (its weight) at the Earth's surface, using the
radius of the Earth as the distance. We also need the Constant of
Proportionality in the Law of Universal Gravitation, G. This value was experimentally determined by Henry
Cavendish in the 18th century to be the extemely small force of 6.67 x 10-11 Newtons
between two objects weighing one kilogram each and separated by one meter.
Cavendish determined this constant by accurately measuring the horizontal force
between metal spheres in an experiment sometimes referred to as "weighing
the earth."
The correct answer between all
the choices given is the third choice or letter C. I am hoping that this answer
has satisfied your query and it will be able to help you in your endeavor, and
if you would like, feel free to ask another question.
