rheonomous

{{short description|Mechanical system whose constraints are dependent on time}}

A mechanical system is rheonomous if its equations of constraints contain the time as an explicit variable.{{cite book |last=Goldstein |first=Herbert |authorlink=Herbert Goldstein |title=Classical Mechanics |url=https://archive.org/details/classicalmechani00gold_639 |url-access=limited |year=1980 |location=United States of America |publisher=Addison Wesley |edition=2nd |isbn=0-201-02918-9 |page=[https://archive.org/details/classicalmechani00gold_639/page/n27 12] |quote=Constraints are further classified according as the equations of constraint contain the time as an explicit variable (rheonomous) or are not explicitly dependent on time (scleronomous).}}{{cite book |last=Spiegel |first=Murray R. |title=Theory and Problems of THEORETICAL MECHANICS with an Introduction to Lagrange's Equations and Hamiltonian Theory |year=1994 |series=Schaum's Outline Series |publisher=McGraw Hill |isbn=0-07-060232-8 |page=283 |quote=In many mechanical systems of importance the time t does not enter explicitly in the equations (2) or (3). Such systems are sometimes called scleronomic. In others, as for example those involving moving constraints, the time t does enter explicitly. Such systems are called rheonomic.}} Such constraints are called rheonomic constraints. The opposite of rheonomous is scleronomous.