Albert, Bernard and Cheryl, again

Classical Mechanics Level 3

Albert, Bernard and Cheryl meet each other after a long time. They meet each other in a room shaped in a form of an equilateral triangle with side 30 $m$ . After seeing each other from a distance along the three corners of the room they become excited. Each person runs in a constant speed 5 $ms^{-1}$ . They run in such a way that Albert runs directly towards Bernard, Bernard towards Cheryl and Cheryl towards Albert.

After how much time in seconds will the three finally meet?

If you think that they will never meet if they continue running in the same way, i.e. $\infty$ . Enter your answer as 999999999999.

The answer is 4.

1 solution

Pradyumna Gupta
Mar 6, 2016

Here the will definitely meet each other the path followed by them is certainly interesting one! They will meet at the centroid of the triangle. Here the distance between two people is 30m . We have to find the the relative velocity of one relative to other along the line joining two people.

5cos60 +5 =7.5m/s

Time = distance/velocity=30/7.5=4 sec

Beautiful solution pradyumna. Liked your approach towards the problem

avi solanki - 5 years, 3 months ago

Albert, Bernard and Cheryl, again

If you think that they will never meet if they continue running in the same way, i.e. ∞ \infty ∞ . Enter your answer as 999999999999.

The answer is 4.

1 solution

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If you think that they will never meet if they continue running in the same way, i.e. $\infty$ . Enter your answer as 999999999999.