A-level Maths Mechanics: How to solve lift problems

[brigidhemingway]

Thank you for such a beautifully clear explanation.

[lynnebilal]

hello, if the lift was accelerating downwards, when we take the forces acting on the lift only do we take the upward reactions only?

[emanuele]

Isnt the normal force the reaction to Fg? Then how do we have a reaction to the reaction force?

[lm]

so just to clarify, would the diagram and equations at 5:34 be identical even if acceleration were to be downward?

[shamirjilani]

Why is it we dont consider the weight of the block 100g if just looking at the lift isnt 100g acting on the lift