An inertial balance is a device that allows the measurement of
inertial mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementa ...
(as opposed to
gravitational mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementa ...
for a regular balance) that can be operated in the
microgravity environment
space
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually cons ...
where weight is negligible (e.g. in the International Space Station.) The principle of operation is based on a vibrating spring-mass system. The frequency of vibration will depend on the unknown mass, being higher for lower mass. The object to be measured is placed in the inertial balance, and a manual initial displacement of the spring mechanism starts the oscillation. The time needed to complete a given number of cycles is measured. Knowing the characteristic spring constant and damping coefficient of the spring system, the mass of the object can be computed according to the
harmonic oscillator model. Alternatively, a calibration of the device with known masses can be performed, so that the spring constant and any appreciable damping will implicitly be accounted for, and need not be separately known or estimated. See the data analysis PDF under External Links below for a discussion of several calibration approaches.
See also
*
Mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...
*
Harmonic oscillator
External links
Inertial mass measurement in the International Space Station(dead link?)
Inertial balance demonstration for the physics classroomSuggestions for inertial balance data analysisA Java applet for a spring-mass system, with three attached PDFs on SHM, driven/damped oscillation, and a spring-mass system with friction
Measuring instruments
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