Uniform circular motion. The moving object travels in a circular path.
The magnitude of linear velocity, acceleration, and centripetal force stays constant, but their direction changes.
The red arrow represents the direction of the linear velocity and the black arrow represents the direction of the
acceleration and resultant force.
Useful equations:
$$
\begin{equation}
F_c = {m v^2 \over r}
v = \omega r
\end{equation}
$$
Mass (\(m\)) | kg |
Radius (\(r\)) | m |
Angular velocity (\(\omega\)) | rad/s |
Linear velocity (\(v\)) | number m/s |
Centripetal force (\(F_c\)) | number N |
Maximum friction force. An object is resting on a spinning surface.
In this scenario, the centripetal force is the force of friction holding the object to the surface.
Useful equations:
$$
\begin{equation}
F_f = \mu F_N = \mu m g \\
F_c = {m v^2 \over r}
\end{equation}
$$
Mass (\(m\)) | kg |
Radius (\(r\)) | m |
Angular velocity (\(\omega\)) | rad/s |
Coefficient of static friction (\(\mu\)) | |
Centripetal force (\(F_c\)) | number N |
Frictional force (\(F_f\)) | number N |
Angled string tension. An object is connected to a point above it
by a string, similarly to a tetherball. The object moves around the post in uniform circular motion,
resulating in a tension force being exerted by the string at an angle \(\theta\). The horizontal component
of the tension force \(F_{Tx}\) is equal to the centripetal force and the vertical component \(F_{Ty}\) is equal
to \(F_g\).
Useful equations:
$$
\begin{equation}
F_{Tx} = {mv^2 \over r} \\
F_{Ty} = mg \\
F_T = \sqrt{{F_{Tx}}^2 + {F_{Ty}}^2} \\
\theta = {\tan}^{-1}({F_{Tx} \over F_{Ty}})
\end{equation}
$$
Mass (\(m\)) | kg |
Radius (\(r\)) | m |
Angular velocity (\(\omega\)) | rad/s |
Linear velocity (\(v\)) | number m/s |
Tension force (\(F_T\)) | number N |
Angle (\(\theta\)) | number degrees |
Uniform Circular Motion Equations
$$
\begin{equation}
a_c = {v^2 \over r} = \omega^2 r \\
F_c = m a_c = {m v^2 \over r} \\[16pt]
F_f = \mu F_N \\
\omega = {2 \pi \over T} \\
v = \omega r \\[16pt]
T = {1 \over f} \\
f = {1 \over T} \\
\end{equation}
$$