Question

A ring, solid sphere, and a disc are rolling down from the top of the same height, then the sequence to reach on surface is?

• A. Ring, disc, sphere
• B. Sphere, disc, ring
• C. Disc, ring, sphere
• D. Sphere, ring, disc

Answer 1

The correct option is B Sphere, disc, ring

Time of descent $\propto$ moment of inertia $\propto \frac{k^2}{R^2}$
${\left(\frac{k^2}{R^2}\right)}_{sphere}=0.4,{\left(\frac{k^2}{R^2}\right)}_{disc}=0.5,{\left(\frac{k^2}{R^2}\right)}_{ring}=1\therefore t_{sphere}<t_{disc}<t_{ring}.$