A flywheel can rotate in order to store kinetic energy. The flywheel is a uniform disk made of a material with a density $\rho $ and tensile strength $\sigma $ (measured in Pascals), a radius $r$ , and a thickness $h$ . The flywheel is rotating at the maximum possible angular velocity so that it does not break. Which of the following expression correctly gives the maximum kinetic energy per kilogram that can be stored in the flywheel ? Assume that $\alpha $ is a dimensionless constant
$\alpha \sqrt {\frac{{\rho \sigma }}{r}} $
$\alpha h\sqrt {\frac{{\rho \sigma }}{r}} $
$\alpha \left( {\frac{h}{{{r^2}}}} \right)\left( {\frac{\sigma }{\rho }} \right)$
$\frac{{\alpha \sigma }}{\rho }$
Why the angular momentum perpendicular to the axis ${L_ \bot }$ in a rotational motion about a fixed axis ?
$A$ hollow sphere of radius $R$ and mass $m$ is fully filled with water of mass $m$. It is rolled down a horizontal plane such that its centre of mass moves with a velocity $v$. If it purely rolls
A particle of mass $m = 5$ is moving with a uniform speed $v = 3\sqrt 2$ in the $XOY$ plane along the line $Y = X + 4$ . The magnitude of the angular momentum of the particle about the origin is .......
A particle is moving along a straight line with increasing speed. Its angular momentum about a fixed point on this line ............
A particle of mass $2\, kg$ is moving such that at time $t$, its position, in meter, is given by $\overrightarrow r \left( t \right) = 5\hat i - 2{t^2}\hat j$ . The angular momentum of the particle at $t\, = 2\, s$ about the origin in $kg\, m^{-2}\, s^{-1}$ is