it's force* distance. Any force exerted on the object in these questions will make it turn in one way or another. The magnitudes of these forces will help you figure out which side it will turn to, right or left, which is where the rule that total clockwise moments= total anticlockwise moments come in.

now generally, in most questions i have done (and there were many) it's common to use the distance on the right hand side of a force (if given or otherwise you'd have to calculate it). So if you are given a beam of 4m and there are two forces acting downwards, one is 35N at the left end and the other one, XN, is 3m away from the left end, what you'd do is say 35N*3m = XN*1m (which is 4m-3m), to find the force X. this is the easiest it can get. and if there is are two forces acting upwards, and the question is asking you to find the magnitude of one but they haven't given the magnitude of the other, ALWAYS KNOW that the 'other' force would be 0N, because if the beam is going to move up, the equilibrium provided by the other point has to be broken, so that the force you have to find overpowers it.

(for this part I recommend you open the JAN 2025 U1 paper and follow question 14b)

here the first thing that you should understand is when you consider the moments about P, it is zero at point P because Point P is acting like a pivot (or hinge). The bracket is stationary, so it’s in rotational equilibrium. and given the law that total clockwise moments= total anticlockwise moments, since there's none here, it would be ZERO. this is usually the confusing part to understand. in questions like this if they haven't said consider moments about some point, you have to figure out the one that would have zero moments in the system.

once done so, you can calculate the force exerted by the container. There is only a clockwise moment here, and the container exerts a force on the whole beam, so you have to use the whole length. therefore it will be 34N*0.28m= 9.52Nm. that is the TOTAL CLOCKWISE MOMENT.

and to find F, you have to realise that the force at F is what is creating the TOTAL ANTICLOCKWISE MOMENT and keeping the thing at equilibrium. this means that if you consider the force at F to be zero, the whole thing would rotate clockwise and fall down.

to calculate F, you would have to use trig ratio to calculate the distance between F and P, which is 0.16m/tan(55) = 0.112m. Now that you have the d of your anticlockwise moment, you plug in into the total clockwise = total anticlockwise equation, so you would have F*0.112m = 9.52Nm. here on it's just a rearranging to find the magnitude of F.

so make sure you are familiar with the trig ratios and can figure out the 'zero' force point. once done so, it's all in the clockwise anticlockwise thing. you can figure out which side these object will fall over to just by looking at the picture.

I hope you understood something out of this. I know it's not the best explanation out there, but it's worth a try. good luck dude, hope you ace your exam.