Mathematical and Physical Journal
for High Schools
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Problem P. 3898. (May 2006)

P. 3898. A horizontal disc of mass m=0,6 kg and radius R=10 cm can be rotated easily about a vertical axle. Along a radius of the disc a sheet is fixed to the disc. (The mass of the sheet is negligible.) A horizontally fired bullet, whose mass is m1=20 g, hits the sheet perpendicularly, and the disc begins to rotate at an angular velocity of \omega=20 s-1. The distance between the axle and the place of impact is r=8 cm. What was the initial speed of the bullet, if a) it is embedded in the sheet; b) it bounced back totally elastically?

(5 pont)

Deadline expired on June 12, 2006.


81 students sent a solution.
5 points:52 students.
4 points:15 students.
3 points:11 students.
2 points:2 students.
0 point:1 student.

Problems in Physics of KöMaL, May 2006