Circular Motion
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General Learning Resources
Average Angular Velocity:
$\omega_{av} = \frac{\Delta \theta}{\Delta t}$
Instantaneous Angular Velocity:
$\omega = \frac{d\theta}{dt}$
Average angular acceleration: $\alpha_{av} = \frac{\Delta \omega}{\Delta t}$
Instantaneous Angular Acceleration:
$\alpha = \frac{d\omega}{dt} = \omega \frac{d\omega}{d\theta}$
Relation Between Speed And Angular Velocity:
$v = r\omega$
and $\vec{v} = \vec{\omega} \times \vec{r}$
Tangential Acceleration (Rate Of Change Of Speed):
$a_t = r \frac{d\omega}{dt} = \omega \frac{dr}{dt}$
Radial Or Normal Or Centripetal Acceleration:
$a_r = \frac{v^2}{r} = \omega^2 r$
Total Acceleration:
$\vec{a} = \vec{a}_t + \vec{a}_r \Rightarrow a = \sqrt{a_t^2 + a_r^2}$

Angular Acceleration:
$\vec{\alpha} = \frac{d\vec{\omega}}{dt} \quad \text{(Non-uniform circular motion)}$
Radius Of Curvature:
$R = \frac{v^2}{a_{\perp}} = \frac{mv^2}{F_{\perp}}$
Normal Reaction Of Road On A Concave Bridge:
$N=m g \cos \theta+\frac{m v^2}{r}$
Normal Reaction On A Convex Bridge:
$N=m g \cos \theta-\frac{m v^2}{r}$
Skidding Of Vehicle On A Level Road:
$v_{\text{safe}} \leq \sqrt{\mu gr}$
Skidding Of An Object On A Rotating Platform:
$\omega_{\max} = \sqrt{\frac{\mu g}{r}}$
Bending Of Cyclist:
$\tan \theta = \frac{v^2}{rg}$
Banking Of Road Without Friction:
$\tan \theta = \frac{v^2}{rg}$
Banking Of Road With Friction:
$\frac{v^2}{rg} = \frac{\mu + \tan \theta}{1 - \mu \tan \theta}$
Maximum And Minimum Safe Speed On A Banked Frictional Road:
$V_{\max} = \left[\frac{rg(\mu + \tan \theta)}{(1 -\mu \tan \theta)}\right]^{1/2}$
$V_{\min} = \left[\frac{rg(\tan \theta -\mu)}{(1 + \mu \tan \theta)}\right]^{1/2}$
Centrifugal Force (Pseudo Force):
$f = m\omega^2 r$
It acts outwards when the particle itself is taken as a frame.
Effect Of Earth’s Rotation On Apparent Weight:
$N = mg - mR\omega^2 \cos^2 \theta,$
where $\theta$ is the latitude at a place.
Vertical Circle:
Various quantities for a critical condition in a vertical loop at different positions.
Conical pendulum:
$T \cos \theta = mg$
$T \sin \theta = m\omega^2 r$
Time period: $T = \sqrt{\frac{2\pi L \cos \theta}{g}}$
Relations among angular variables:
Initial angular velocity: $\omega_0$
$\omega = \omega_0 + \alpha t$
$\theta = \omega_0 t + \frac{1}{2} \alpha t^2$
$\omega^2 = \omega_0^2 + 2 \alpha \theta$