Answer to Question #149186 in Mechanics | Relativity for Banawit Tansirisittikul

Question

. A flywheel used for storing energy consists of a uniform disk of mass 1.5x105
kg and radius 2.2 m that
rotates at 3000 rev/min about its center of mass Find its kinetic energy.

Answer 1

$Kinetic\space Energy=\frac{1}{2}\times I\times w\times\ w \\whereby: \space \\ \qquad I=moment \space of \space \space Inertia \\ \qquad w=rotational\space velocity(rpm) \\Therefore;\\\qquad I=k\times m\times r \times r \\ \quad =\frac{1}{2}\times 1.5\times 10^{5} \times\ 2.2\times 2.2\\ \quad = 75000\times 2.2\times 2.2\\ \quad=363000 \\ Thus:\\ Kinetic\space Energy= \frac{1}{2}\times 363000\times\ 3000\times 3000\\ \quad = 1,629,000,000,000Joules \\ \quad=1.629\times10^{12}Joules.$