potential energy
where v = dr/dt is the velocity of the point of application of the conservative force F. For example, if F = −k(x−l)i, as in Hooke's law, then 
, taking the potential energy to be zero when x = l. In problems involving gravity near the Earth's surface it may be assumed that the gravitational force is given by F =−mgk, and then, taking the potential energy to be zero when z = 0, V = mgz. See also gravitational potential energy.
Potential energy has the dimensions ML2T−2, and the SI unit of measurement is the joule.
- rectilinear motion
- recurrence relation
- recurrent
- recurring decimal
- recursion theory
- reduce
- reduced echelon form
- reduced set of residues
- reductio ad absurdum
- reduction formula
- redundancy
- redundant
- re-entrant
- reflection
- reflex angle
- reflexive relation
- reflexive space
- Regiomontanus
- region
- regression
- regression to the mean
- regular function
- regular graph
- regular polygon
- regular polyhedron