How Often Will Two Children Swinging at Different Rates Sync Up in a Minute?

[aknita]

1. Two children are swinging on swings side by side. One completes 20 cycles in 1.0 min while the other completes 26 cycles in 1.0 min. If they start out together, how many additional times will they be swinging together during that minute? Explain.
2. The attempt at a solution
f=N/t
f1=20/60
=.333
f2=26/60
=.433

B.F=f2-f1
=.433-.333
=.1

.1=N/60

N=6 timesthe answer is correct, but i was wondering whether the way i calculated it was the proper method.
thanks in advance.

 

[andrevdh]

Hi aknita,
welcome to PF. Hope we can be of help to you.

The question do not indicate along which lines the problem should be solved. But if it were an exam question the explanation might count more than half of the marks. Personally I would rather use the periods to do the calculation.

So, how did you came to the answer? Can you justify your approach?