# Normal contact force with a light string

I started mechanics this year. There was a question about a smooth ring threaded on a light string at rest. The string's ends were each connected to a rod forming an isosceles triangle with the ring at one vertex. We were asked to find the tension in the string. My teacher said that since the string is light, there would be no normal contact force pair between the ring and the string. I don't understand why for 2 reasons : 1. The rope, eventhough m=0 for ease, is still rope. It is a surface on which the ring rests. Why won't contact forces exist. 2. If there are no normal contact forces, how is the ring at rest. The tensions aren't "pulling" on the ring. What am I missing?

• Your explanation of the situation isn't clear, can you explain in greater details. – TechDroid Mar 10 '19 at 10:26
• My view is that the ring itself has it's weight and the normal contact force. The bit of rope there has the tension from two sides and the other pair of the normal contact. – Sal_99 Mar 10 '19 at 10:57
• Can you provide an image of the setup, maybe hand drawn, that will better picture the situation than just words – TechDroid Mar 10 '19 at 11:21
• I have put a picture of my interpretation. – Sal_99 Mar 10 '19 at 11:49
• Can you edit the main question so it explains the image because it isn't clear how the "rope view" and "ring view" merge. – TechDroid Mar 10 '19 at 11:55