# Problem P. 4394. (December 2011)

**P. 4394.** A semi-cylinder is cut out of a block and the block is fixed on the horizontal surface. A small body of mass *m* is released at the top of the cylinder shaped hole. (Friction is negligible.)

*a*) What is the force that the small body exerts on the block at the lowest point of its path?

*b*) If the block is able to move on the horizontal surface without friction, then the force exerted on the block by the small body at the lowest point is . By what fraction is the mass of the block greater than the mass of the small body?

(5 pont)

**Deadline expired on January 10, 2012.**

Sorry, the solution is available only in Hungarian. Google translation

**Megoldás.** \(\displaystyle a)\) \(\displaystyle 3mg.\)

\(\displaystyle b)\) \(\displaystyle M=4m\).

### Statistics:

115 students sent a solution. 5 points: 52 students. 4 points: 10 students. 3 points: 15 students. 2 points: 12 students. 1 point: 16 students. 0 point: 6 students. Unfair, not evaluated: 4 solutions.

Problems in Physics of KöMaL, December 2011