You would account for the weight :P This video is more to show how to find the directions of the frictional force and the processes of solving friction-type questions. I did not include weight in the diagrams to simply save space as we already know the direction is downward and the magnitude is typically provided. I was on the fence about including the normal force as well as the direction is easily figured out but since many students associate frictional force and normal force I included it. I hope this explanation helps as it is a great point :)
hi clayton, i really appreciate your quality here, but just wondering: at 4:26 figure B, the frictional force also generates a moment in a direction opposite of M which is the reason why it is harder to start moving a car than it is to keep it moving right?
I don't understand why we account for normal force which is reaction to weight and ignore weight in equilibrium?
You would account for the weight :P This video is more to show how to find the directions of the frictional force and the processes of solving friction-type questions. I did not include weight in the diagrams to simply save space as we already know the direction is downward and the magnitude is typically provided. I was on the fence about including the normal force as well as the direction is easily figured out but since many students associate frictional force and normal force I included it. I hope this explanation helps as it is a great point :)
Thank you very much for clarification.
hi clayton, i really appreciate your quality here, but just wondering: at 4:26 figure B, the frictional force also generates a moment in a direction opposite of M which is the reason why it is harder to start moving a car than it is to keep it moving right?