Mathematical and Physical Journal
for High Schools
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# Problem P. 4332. (March 2011)

P. 4332. Two balls, made of soft copper alloy of specific heat capacity 400 J/(kg.K), collide head on. The initial speeds of the two balls, A and B, were the same and oppositely directed. After the collision ball A stops and ball B bounces back with the same speed as it had before the collision. Because of the collision the temperature of the balls increased with C. At least what was the speed of the balls before the collision?

(4 pont)

Deadline expired on April 11, 2011.

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

Megoldás. A golyók ütközés előtti sebessége legalább $\displaystyle v=20~\rm m/s$ volt.

### Statistics:

 126 students sent a solution. 4 points: 94 students. 3 points: 4 students. 2 points: 7 students. 1 point: 13 students. 0 point: 7 students. Unfair, not evaluated: 1 solutions.

Problems in Physics of KöMaL, March 2011