The rectangular plate is tilted about its lower edge by a cable tensioned at a constant 600 N. Determine and plot the moment of this tension about the lower edge AB of the plate for the range 0 ≤ θ ≤ 90°

Explanation:

From the figure , it is clear that moment of tension is balanced by moment of weight of plate about the line AB which is acting as axis . If W be the weight of plate ,

moment of tension about AB = moment of weight W about line AB

= W x 2.5 cosθ

moment of tension about AB = 2.5 W cosθ

here only variable  is cosθ which changes when θ changes

So, moment of tension about AB varies according to cosθ.

When θ = 0

moment of tension about AB = 2.5 W x cos 0 = 2.5 W . It is the maximum value of moment of tension .

When θ = 90°

moment of tension about AB = 2.5 W cos 90 = 0

moment of tension about AB = 0

So graph of moment of tension about AB will vary according to graph of

cosθ . It has been shown in the file attached .

a and b sometimes have a positive value

see earlier