how should we calculate weight of earth ?

Question

mani_jha · Answer

Drop an object from a known height h. Measure the time it takes to reach the ground.(let it be t). Calculate the acceleration using the equations of motion(do you know them?).
The acceleration will come out to be equal to 9.801 m/s^2 approximately. What is the force of attraction between the object and the earth? If m is the object's mass and M is the earth's mass, it is:
$$F=GMm/r^2$$
where r=6400km is the earth's radius.
Now, acceleration is equal to0 Force/Mass, isn't it?
$$9.801=(GMm/r ^{2})/m$$
or,$$9.801=GM/r ^{?}$$
Using G=6.67x10^-11, Calculate M.
Clear?

anonymous · Answer

Thank you. its nice and very helpful :) thank again and good day

mani_jha · Answer

No problem :). Are you from India?

anonymous · Answer

yes and what about you ?

mani_jha · Answer

me too ;)

anonymous · Answer

thats good nice to meet you :)