Use the second condition for equilibrium (net = 0) to calculate F p in Example 9.1, employing any data given or solved for in

Use the second condition for equilibrium (net π = 0) to calculate F_p in Example 9.1, employing any data given or solved for in part (a) of the example.

Data given in Example 9.1

The two children shown in Figure 9.8 are balanced on a seesaw of negligible mass. (This assumption is made to keep the example simple—more involved examples will follow.) The first child has a mass of 26.0 kg and sits 1.60 m from the pivot.

(a) If the second child has a mass of 32.0 kg, how far is she from the pivot?

(b) What is F_P, the supporting force exerted by the pivot?

Strategy

Both conditions for equilibrium must be satisfied. In part (a), we are asked for a distance; thus, the second condition (regarding torques) must be used, since the first (regarding only forces) has no distances in it. To apply the second condition for equilibrium, we first identify the system of interest to be the seesaw plus the two children. We take the supporting pivot to be the point about which the torques are calculated. We then identify all external forces acting on the system.

m W Fp 12 m W