`F_W = mg`

This Force of Weight equation, F_W = M⋅g, computes force known as weight based on the mass (M) and the acceleration due to gravity (g).  

INSTRUCTIONS: Choose units and enter the following:

• (m) Mass of the object.
• (g) acceleration due to gravity.  (default of 9.8 m/s²)

Force of Weight (F_w):  The calculator computes the force (F_W) in newtons.  However, this can be automatically converted to other force units via the pull-down menu.

The Math / Science

The force of weight formula is a form Newton's 2nd Law of motion and the formula F= M•A.  Where acceleration is the acceleration due to Earth's gravity which is approximately 9.8 m/s² on the surface of the Earth at Sea Level.

Acceleration Due to Gravity (g)

The acceleration due to gravity is depends on the masses of the two attracting bodies (e.g. you and the Earth).  In the case of acceleration due to gravity on the Earth, the number is not constant because the Earth is not a perfect sphere made of uniform material.  The greatest factor is the fact that Earth has a bulge at the equator.  The net result is that acceleration due to gravity can be estimated by one's latitude.  The International Gravity Formula provides a good estimation of the acceleration due to gravity (d) as a function of latitude.

References

• Light and Matter(Dr. Benjamin Crowell) Chapter 4.3 Newton's Second Law
• Light and Matter(Dr. Benjamin Crowell) Chapter 5.2 Classification and behavior of forces
• Light and Matter(Dr. Benjamin Crowell) Chapter 5.3 Analysis of forces