Block sliding down a wedge, all resting on a balance

[dorothy]

Homework Statement

Hello! I am now working on an exercise which is related to mechanics. I calculated it wrongly. Attached is the answer. I have no idea how to do c(ii), I don’t understand how cos theta is applied in that question. Please explain it to me if you get it. thanks a lot!

Relevant Equations

F=ma
a=mg*sin theta

 

[kuruman]

Consider the wedge block sliding down on the rough incline. Please answer the following three questions which are an elaboration of the hint in c(ii).

1. What is the magnitude and direction of the net force on the sliding block? It cannot be zero because the block is accelerating.
2. What is the force exerted by the block on the wedge? It must be a 2D vector with horizontal and vertical components.
3. What must be true for the wedge to remain stationary?

Bonus question: What is the reading of the balance when the block is accelerating?