Answer to Question #273900 in Physics for Mark

Question

sakuragi is spinning a basketball with a radius of 0.15 m on the tip of his finger . Determine the mass of the ball if it's moment of inertia is five point 568 x 10 negative 3 kg x m squared

Answer 1

Let's model the ball with a hollow sphere. Then its moment of inertia is given as follows:

$$I = \dfrac23mr^2$$

where $m$ is the mass of the ball and $r = 0.15m$ is its radius. Since $I = 5.568\times 10^{-3}kg\cdot m^2$, find:

$$m = \dfrac{3I}{2r^2}\\ m = \dfrac{3\cdot 5.568\times 10^{-3}}{2\cdot 0.15^2} \approx 0.37kg$$

Answer. 0.37 kg.