Centrifugal Force Formula
In a reference frame rotating with an angular velocity \(\boldsymbol{\omega}\), the centrifugal force \(\mathbf{F}_{\mathrm{cf}}\) acting on an object of mass \(m\) at a position vector \(\mathbf{r}\) from the origin is given by the vector formula: \(\mathbf{F}_{\mathrm{cf}} = -m \boldsymbol{\omega} \times (\boldsymbol{\omega} \times \mathbf{r})\). This formula shows the force is directed perpendicular to the axis of rotation and outwards.
The vector formulation of centrifugal force provides a complete description of its magnitude and direction. The formula \(\mathbf{F}_{\mathrm{cf}} = -m \boldsymbol{\omega} \times (\boldsymbol{\omega} \times \mathbf{r})\) uses the vector cross product. Here, \(\boldsymbol{\omega}\) is the angular velocity vector, which points along the axis of rotation. The term \(\boldsymbol{\omega} \times \mathbf{r}\) represents the tangential velocity of the point. The second cross product, \(\boldsymbol{\omega} \times (\boldsymbol{\omega} \times \mathbf{r})\), results in a vector that points radially inward, representing the centripetal acceleration. The negative sign in the formula flips this direction, resulting in a force vector that points radially outward from the axis of rotation. The magnitude of this force can be simplified to \(m \omega^2 r_{\perp}\), where \(r_{\perp}\) is the perpendicular distance from the mass to the axis of rotation. This mathematical precision is crucial for analyzing motion in rotating systems, such as the dynamics of machinery, planetary atmospheres, and spacecraft. It is a key component in the transformation of Newton’s second law from an inertial frame to a rotating frame, which also includes the Coriolis force and the Euler force.
This formulation is a direct consequence of differentiating a position vector in a rotating frame. The total acceleration in an inertial frame is the sum of the acceleration observed in the rotating frame, the centripetal acceleration, the Coriolis acceleration, and the Euler acceleration. When we rearrange Newton’s second law (\(\mathbf{F}_{\mathrm{real}} = m \mathbf{a}_{\mathrm{inertial}}\)) for the rotating frame, these acceleration terms move to the force side of the equation and appear as fictitious forces with a negative sign. The centrifugal force is thus the term \(-m(\boldsymbol{\omega} \times (\boldsymbol{\omega} \times \mathbf{r}))\).
UNESCO Nomenclature: 2210
– Mechanics
Precursors
- Newton’s second law of motion
- development of vector calculus and the cross product
- Euler’s work on the kinematics of rigid bodies
- Lagrange’s formulation of mechanics
Applications
- computational fluid dynamics (cfd) for turbomachinery
- satellite orbital mechanics and attitude control
- vehicle dynamics simulation
- robotics and manipulator arm dynamics
- weather modeling (in conjunction with coriolis force)
Potential Innovations Ideas
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Related to: centrifugal force, vector formula, cross product, angular velocity, rotating reference frame, classical mechanics, fictitious force, centripetal acceleration, coriolis force, euler force.