Answer: see example due to variation of factor
Explanation: w = m x g
Weight= Mass (in kg) x Gravity (9.8m/s)
To get to kg from lbs take your weight divide by 2.2lbs well get you to kg
Example
Let's say a boy weighs 145lbs
145kg/2.2lbs=66kg
Now we use the equation
w=m x g
65kg*9.81m/s=637.65N