As part of a problem, I was required to make a free body diagram for the following system:
It is given that the platform and the man have the same mass $m$. Apart from the forces due to tension, my initial thought was that the platform would apply a normal force $N$ upwards due to the weight $mg$ of the man.
But in the solution to the problem, apparently, there is a normal force $N$ acting downwards. The normal is force is given by the man, to the platform. Why is that? Why is the normal force acting in the direction of weight?
For most other problems, I am used to applying the normal force upwards, usually given by a platform/wedge to the object on top of it, to balance out the downward force given by the object due to its weight. But in this case, the normal force is acting downwards and I cannot understand the reason why.
Please explain this to me.