Mathematical and Physical Journal
for High Schools
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Problem P. 4268. (September 2010)

P. 4268. A physics teacher often went to skate to a nearby frozen lake. Once he could reduce his speed to one third of its original value along 16 m skidding, and then it took him 1 more second to stop. How much distance did he cover during the braking. On another day he had the same initial speed and suddenly he noticed a crevasse in the ice 20 m in front of him. At what distance from the crevasse could he stop, if his reaction time is 0.1 s, and he used his familiar braking technique.

(4 pont)

Deadline expired on October 11, 2010.

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

Megoldás. A teljes fékezés során 18 métert tett meg. A másik esetben a rianástól 80 cm-re tudott megállni.


285 students sent a solution.
4 points:200 students.
3 points:30 students.
2 points:14 students.
1 point:4 students.
0 point:30 students.
Unfair, not evaluated:7 solutionss.

Problems in Physics of KöMaL, September 2010