4.) While on an archaeological dig, you unearth a small ceramic cylinder. Your colleagues
are puzzled by the historical purpose of the cylinder. They decide it might help to
know if the cylinder is hollow or solid. Some members of your team suggest high tech
imaging to determine this, but you know a better way! You let the cylinder roll without
slipping down a ramp of length 0.5 m; the ramp is angled at 30°. After the cylinder
reaches the bottom, it continues to roll without slipping on a smooth flat stretch and
you see that it takes 1.6 seconds to travel a linear distance of 2.5 m. Is the cylinder
solid or hollow? [Hint: $I = \#MR^2$. Calculate the number in front of $MR^2$ and
compare with the known moments of inertia.]
Answer: It's hollow. What is in there!?