Amir is playing with his older brother Ajith. They are playing on the swing in the figure below. Amir is at point $B$ which is $140 \mathrm{~cm}$ from the fulcrum $F$. Ajith is at point $A$ which is $100 \mathrm{~cm}$ from $F$. If Amir's weight is $200 \mathrm{~N}$, how much force must Ajith exert to make Amir go up?
[280 N]
