A uniform plank of length 5.3 m and weight 228 N rests horizontally on two supports, with 1.1 m of the plank hanging over the right support (see the drawing). To what distance x can a person who weighs 446 N walk on the overhanging part of the plank before it just begins to tip?

Answer 1

Set the moment about the right support equal to zero and assume that no force is exrted by the left support. (That will be the tipping condition). The weight of the plank acts through the center of mass, 1.55 m left of the right support. Thus,

228 * 1.55 = 446 * x

Solve for x.

Answer 2

1.0008