What is the mass of a person if they have a weight of 999.0 N near the earth’s surface?

Answer 1

weight (in Newtons) is the force of gravity between the person and the Earth. To solve this we use newton's second law:

F = ma

where F = 999.0 N and a = 9.806 m/s² (the acceleration due to gravity*)

solving for m gives:

m = F/a = 999.0N / 9.806 m/s² = 101.9 kg

*Normally, g is written only with 2 decimal places or fewer (e.g. 9.81 m/s²), I used 3 decimal places so g would also have 4 significant figures like what was given.