Reaction forces - vector depiction

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When part of a body exerts force on a stable or unmoving surface (like the floor or the handle of a walker), it produces an equal and opposite reaction force.

Point of application	Center of pressure of body part on stable surface.
Line of application	the direction in which the body part applies force to a stable surface
Direction	opposite to the direction in which the body part applies force to a stable surface.
Magnitude	arbitrary; drawn to scale

Ground reaction or floor reaction forces are extremely helpful in understanding human movement patterns like walking.

Last updated 12-4-97 ©Dave Thompson PT