# Problem P. 4372. (October 2011)

**P. 4372.** Two trolleys of mass 2 kg, lying along a line, are at rest on a horizontal tabletop. On one of them there is a spring as well as shown *in the figure.* The trolley on the left is given an initial speed of 5 m/s, and it collides with the other one on the right. What is the energy stored in the spring when it is the shortest?

(3 pont)

**Deadline expired on November 10, 2011.**

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

**Megoldás.** \(\displaystyle \frac{1}{4}mv^2=12{,}5~\)J.

### Statistics:

215 students sent a solution. 3 points: 110 students. 2 points: 23 students. 1 point: 61 students. 0 point: 9 students. Unfair, not evaluated: 12 solutions.

Problems in Physics of KöMaL, October 2011