Question

How would gravitational mass and inertial mass change in an elevator (if at all)? Why is this true?

Answer 1

Inertial mass. This is mainly defined by Newton's law,s F = ma, which states that when a force F is applied to an object, it will accelerate proportionally, and that constant of proportion is the mass of that object. To determine the inertial mass, you apply a force of F Newtons to an object, and F/a will give you the inertial mass m

2) Gravitational mass. This is defined by the force of gravitation, which states that there is a gravitational force between any pair of objects, which is given by

F = G m1 m2/r2

where G is the universal gravitational constant, m1 and m2 are the masses of the two objects, and r is the distance between them. This, in effect defines the gravitational mass of an object.

As it turns out, these two masses are equal to each other as far as we can measure. Also, the equivalence of these two masses is why all objects fall at the same rate on earth.

If you stand on scale a elevator accelerating upward, you feel heavier because elevator floor presses harder on your feet, and scale will show higher reading than when elevator is at rest. On the other hand, when elevator accelerates downward, you feel lighter.

So inertial mass will change in an elevator while gravitational mass will not change