.: A ladder is an arrangement which is used for climbing on the walls. It consists of two long uprights of wood or iron and connected by many cross bars. These cross bars are called as rungs and provide steps for climbing. The figure given below shows a ladder AB with its end A resting on ground and end B leaning against the wall. The ladder is acted upon by following set of forces:
(1) Weight W acting downwards at the midpoint of it.
(2) Normal reaction Rh and friction force Fh = µRh at end B leaning against wall. As the ladder has a tendency to slip downwards, friction force will be acting upwards. If the wall is smooth (µ = 0), friction force will be zero.
(3) Normal reaction Ra and friction force Fa =µRa at end A resting on floor. As the ladder, upon slipping, tends to move away from wall, the direction of friction force will be towards wall.
By applying equilibrium conditions, the algebraic sum of horizontal component and vertical component of forces would be zero.