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Science/physics

Help please....
Basically there are four aliens on a planet. They want to go on a sea-saw. The end seats on the sea-saw are 2m from the pivot, and the middle seats are 1m from the pivot. The Aliens way 400N, 300N, 200N and 100N - which two can sit on the sea-saw (on any of the seats) and make it balance? It'd be a huge help if you at least help me work out the answer! :smile:

Reply 1

MangoFreak

Do you know how to calculate a moment? If so, know that when the see-saw is balanced, the sum of the moments exerting a turning force in each direction (clockwise and anti-clockwise) will be equal.

So, total moment clockwise about the pivot = total moment anticlockwise about the pivot

Reply 2

Kallisto

Entertainment Forum Helper

Sounds after the lever principle. Thus the balance which you are look for is: F1 * a = F2 * b. 'a' and 'b' are the levers of the sea-saw, while 'F1' and 'F2' are the forces which impact on both sides of the sea-saw.