How to Use Inertia to Find Mass

One of the great things about Newtonian equations is that, using only a few known variables, you can determine the others. Newton's laws of physics, and the subsequent equations, delineate a set of given facts about physics that allows you to determine the mass by knowing inertia. The first law states that a body in motion will stay in motion until acted upon by another force. The second law dictates that this relationship is F = m * a, where "F" is the force, "m" is the inertial mass and "a" is the acceleration of the object. You can rearrange this equation to state that m = F / a and determine the value of m by using the force of the object with known mass that struck the object with unknown mass.

Things You'll Need

• Digital scale
• Calculator

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Instructions

1. • 1

     Look up the mass of the known object from the given information or from a table. If none was furnished, weigh the object on a scale in grams. Divide the result by 9.81.

   • 2

     Multiply the given acceleration value with the mass value. This is the force of the known object, which will also be the force of the unknown object.

   • 3

     Divide the force by the acceleration value given for the unknown object. This is the inertial mass of that object.

   • 4

     Weigh the unknown object on a scale in grams. Divide the result by 9.81. This is the gravitational mass. This mass should equal the result you calculated for the inertial mass.