Question

A uniform ladder of length 20.0m and weight 750 N is propped up against a smooth vertical wall with its lower end on a rough horizontal surface. The coefficient of friction between the ladder and this horizontal surface is 0.40.

(a) Draw a diagram for the ladder showing all the forces acting on the ladder.

(b) Work out and add the numerical values of each force clearly showing your justification in each case.

(c) Hence, calculate a value for the angle between the ladder and the wall if the ladder just remains in stable equilibrium.

Answer 1

a. can't do drawings here,
On the wall, there is a horizontal force out of the wall at the top of the ladder
On the base, there is a vertical force from the floor upwards, and a horizontal force (friction) pushing inward towards the wall
At ladder midength, there is a force dowward(weight).
that is your diagram.

So now sum vertical forces: You only have two (weightladder and floor upward).
Sum horizontal foces: wall force and friction at base.
Sum moments about any point: I recommend the floor contact point, you have ladder weight, and wall force then.

The angle should come put pretty quickly on the moment equation.

Answer 2

I have completed a but I just don't understand b and c. Please help me asap!!!!