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P. 4384. A small ball of mass m=0.1 kg is attached to a =1 m-long thread and is hung to a horizontal peg. The small ball is at rest and another small ball of mass M=0.2 kg, is projected from the ground and collides with it, such that the collision is totally elastic and head on, and after the collision the ball at the end of the thread completes a whole circle around the peg. The distance between the peg and the ground is 2.

a) What is the least distance of x shown in the figure?

b) What is the initial velocity of the projected ball? (Speed and direction.)

(5 points)

Deadline expired on 12 December 2011.

Google Translation (Sorry, the solution is published in Hungarian only.)

Megoldás. $\displaystyle a)$ $\displaystyle x\ge 2{,}37$ m.

$\displaystyle b)$ $\displaystyle \alpha=40{,}2^\circ$ és $\displaystyle v_{0}=6{,}87~$m/s.

Statistics on problem P. 4384.
 98 students sent a solution. 5 points: 53 students. 4 points: 17 students. 3 points: 25 students. 2 points: 2 students. 1 point: 1 student.

• Problems in Physics of KöMaL, November 2011

•  Támogatóink: Morgan Stanley