If a person weighs 720N. The persons mass is?

Answer 1

The weight (in newtons, N) of an object is given by:

F = m g

where m is the mass (in kilograms, kg), and g is Earth's gravity (which is about 9.8 newtons per kilogram, 9.8 N kg-1, though it varies slightly depending on where in the world you are).

So m = F / g

= 720 N / 9.8 N kg-1

= 73.5 kg (approximately) Notice that the value for g is around 10, so you can estimate the weight of an object by multiplying its mass by 10 (for whole numbers of kilograms, you just put a zero on the end of the number), or you can estimate the mass of an object by dividing its weight by 10 (where there is a zero on the end of the weight, you can just remove it to estimate the mass). So since the weight is 720 N, this shows that the mass is around 72 kg.