Calculate the difference between the magnitude of the gravitational force and the magnitude of the normal force exerted on a 100 kg object at the equator. Which of the two forces is equal in magnitude to the weight of the object?

Answer 1

The "normal force" is the measured weight.

Gravitational force MINUS weight equals the centripetal force, M V^2/R
where R is the radius of the Earth and V is the Earth rotational velocity at the equator, 464 m/s

For a 100 kg object, the difference is
100*(464)^2/6380*10^3 = 3.8 N

which is about 0.85 pound.