Answer:
b. The side the boy is sitting on will tilt downward
Explanation:
Initially, the seesaw is balanced because the torque exerted by the boy is equal to the torque exerted by the girl:
[tex]\tau_b = \tau_g\\W_b d_b = W_g d_g[/tex]
where
Wb is the weight of the boy
db is the distance of the boy from the pivot
Wg is the weight of the girl
dg is the distance of the girl from the pivot
When the boy moves backward, the distance of the boy from the pivot ([tex](d_b)[/tex] increases, therefore the torques are no longer balanced: the torque exerted by the boy will be larger, and therefore the side of the boy will tilt downward.
