Inertial Mass
The only apparent difference between inertial mass and gravitational mass is the method used to determine them.
Gravitational mass is measured by comparing the force of gravity of an unknown mass to the force of gravity of a known mass. This is typically done with some sort of balance. Equal masses will match on a balance because the gravitational field applies to them equally, producing identical weight. This assumption breaks down near supermassive objects such as black holes and neutron stars due to tidal effects. It also breaks down in weightless environments, because no matter what objects are compared, it will yield a balanced reading.
Inertial mass is found by applying a known net force to an unknown mass, measuring the resulting acceleration, and applying Newton's Second Law, m = F/a. This gives an accurate value for mass, limited only by the accuracy of the measurements. When astronauts need to be measured in the weightlessness of free fall, they actually find their inertial mass in a special chair called a body mass measurement device (BMMD).
No physical difference has been found between gravitational and inertial mass. In experimental measurements, the two always agree within the margin of error for the experiment. Einstein used the fact that gravitational and inertial mass were equal to begin his General Theory of Relativity in which he postulated that gravitational mass was the same as inertial mass, and that the acceleration of gravity is a result of a 'valley' or slope in the space-time continuum that masses 'fell down' much as pennies spiral around a hole in the common donation toy at a chain store. Dennis Sciama later showed that the reaction force produced by the combined gravity of all matter in the universe upon an accelerating object is mathematically equal to the object's inertia, but this would only be a workable physical explanation if by some mechanism the gravitational effects operated instantaneously.
Since Einstein used inertial mass to describe special relativity, inertial mass is closely related to relativistic mass and is therefore different from rest mass.
Read more about this topic: Principle Of Inertia (physics), Interpretations
Other articles related to "mass, inertial mass":
... In physics, there are two distinct concepts of mass the gravitational mass and the inertial mass ... The gravitational mass is the quantity that determines the strength of the gravitational field generated by an object, as well as the gravitational force ... The inertial mass, on the other hand, quantifies how much an object accelerates if a given force is applied to it ...
... between at least seven attributes of mass, or seven physical phenomena that can be explained using the concept of mass The amount of matter in certain types of samples can be exactly ... The mass of an exact sample is determined in part by the number and type of atoms or molecules it contains, and in part by the energy involved in binding it together (which contributes ... Inertial mass is a measure of an object's resistance to changing its state of motion when a force is applied ...
... Inertia Sweep an inertia dyno system provides a fixed inertial mass flywheel and computes the power required to accelerate the flywheel (the load) from the starting to ... The actual rotational mass of the engine (or engine and vehicle in the case of a chassis dyno) is not known, and the variability of even the mass of the tires will ... to accelerate the dyno and engine's/vehicle's rotating mass ...
... Mass as a measure of quantity is to be considered dimensionally distinct from mass as a measure of inertia ... in fluid mechanics and thermodynamics) to distinguish between mass as a measure of inertia (inertial mass), and mass as a measure of quantity (substantial mass) ... We wish to find the rate of mass flow of a viscous fluid through a circular pipe ...
Famous quotes containing the word mass:
“Like Freud, Jung believes that the human mind contains archaic remnants, residues of the long history and evolution of mankind. In the unconscious, primordial “universally human images” lie dormant. Those primordial images are the most ancient, universal and “deep” thoughts of mankind. Since they embody feelings as much as thought, they are properly “thought feelings.” Where Freud postulates a mass psyche, Jung postulates a collective psyche.”
—Patrick Mullahy (b. 1912)