Moments in Balance? Joe weighs 6000 N, and sits 1.5m from the centre of the seesaw...?

Question

Sebastian sits 2m from the centre of the seesaw to balance it. How much does he weigh?

Please tell me how to work this out..

Answer 1

he's right

Answer 2

It's pretty simple, really. Since Joe weighs 6000 N, and he's sitting 1.5m from the fulcrum, then the force that he exerts on the seesaw is 6000 x 1.5 = 9000 Newton-meters. If Sebastian wants to balance him when he's sitting 2m away, then that means that 9000 / 2 = 4500. So Sebastian is 4500 N.