REACTION FORCES ON A LADDER LEANING ON A ROUGH WALL

The determination of the reactions on a ladder is discussed including friction against the wall. In a recent article, this problem was studi ed considering elastic compression and it was argued that an additiona l condition holds that allows one to find all the reactions. We show t hat this condition is incorrect for typical ladders, when flexion is i mportant. We clarify the issues of static determinacy by means of an a nalysis that takes into account both compression and flexion. We find that when the climber arrives at the top, the result depends on which deformation prevails. We conclude that the reactions can never be dete rmined using only statics, because there is no way to ascertain which kind of deformation dominates, and so which limiting condition will be attained, if any. (C) 1996 American Association of Physics Teachers.