1. The problem statement, all variables and given/known data 2. Relevant equations principle of moments newton's 3rd law 3. The attempt at a solution Okay. I am not asking how to solve this question. I just have a little misunderstanding of the concept of the Newton's Third Law. I will get straight to the point. For example, in this question, should the reaction from the peg C which is perpendicular to the rod be equals to the sum of forces acting on the rod ( which includes friction ) resolved in the direction of the reaction or is it just equal to the force acting at the point of contact at C ( aka R=W sin θ ) Equilibrium of forces tells me that the former is true but intuitively, I do not see how the frictional force acting on the rod near the ground can affect or can be transferred to the point of contact between the peg and the rod. Can someone clearly enlighten me and help me clear this confusion? And...this may be a little stupid to ask please bear with me. I have been wondering why I do not experience a large pain on my palm when I push the air around my surroundings. Well due to Newton's third Law, a force that I exert on the air molecules should conjure an equal reaction force from the air molecules on my palm right? Or is it not? And if the former is true, since the force acting on my palm is equal to the force I conjure and since there are millions of air molecules I act upon, shouldn't I feel an extremely large force acting on my hand? Uhmmmm....well I am confused, so can someone enlighten me on this topic? Thanks!