Alice and Bob are sat on a seesaw. The seesaw is in static equilibrium. Alice weighs 500N and is sat 0.5m to the left of the pivot. If Bob weighs 800N, how far from the pivot on the right is he sat? What happens if Bob moves closer to the pivot?

First of all draw a diagramIf the seesaw is in static equilibrium this means:There is no net force on the seesawThere is no net moment on the seesawAs a result the anti clockwise moments about the pivot equal the clockwise momentsA moment (Nm) is calculated by force (N) x distance(m)Anticlockwise moment (from Alice) = force x distance = 500 x 0.5 = 250NmClockwise moment (from Bob) = Anticlockwise moment = 250Nm250= 800 x d (where d is the distance from the pivot to Bob on the right hand side of the pivot)d = 0.31m (2S.F)If bob moves closer to the pivot, d decreases and the clockwise moment decreases.As the anticlockwise moment stays the same, this means that there is a resultant moment anticlockwise, and thus the see saw tilts anticlockwise