Three forces act on a hockey puck as it slides across the ice, and it is in equilibrium. The force F is applied at the center and has a magnitude of 25 N. The force F1 is applied at the top edge, and F2 is applied half way between the center and the bottom edge. Find the magnitude of F1 and F2.

Question

I do not understand what to do since there is only one value given.

Answer 1

Conditions of equilibrium are
1/ the sum of forces in a plane is zero
2/ the sum of the torques around the axis of the plane is zero.
Therefore,
F =F1+F2 ..............(1)
F1•R = F2•(R/2) .......(2)
From (2) F2=2F1.
Plug it in (1) and obtain
F =F1 + 2•F1 =3•F1.
F1 =21/3 = 7 N
F2 = 2F1 =14 N.