نیروی ِ مرکزی niru-ye markazi
*Fr.: force centrale*
A → *force* that is always directed toward a fixed point
and whose → *magnitude* depends only on the distance
from that point.
Mathematically, *F* is a central force if and only if:
*F* = *f*(r)**r**_{1} =
*f*(r)**r**/*r*,
where **r**_{1} = **r**/*r* is a unit
→ *vector*
in the direction of **r**. If *f*(r) < 0 the force
is said to be → *attractive* toward the source.
If *f*(r) > 0 the
force is said to be → *repulsive*
from the source.
In other words, a central force is one whose → *potential*,
*V(r)*, depends only on the → *distance*
from the source. → *Gravitational force*
and → *electrostatic force*
are central, with *V(r)*∝ 1/*r*. → *central*; → *force*. |