The present study examines university student collaborations and interactions on an online introductory physics course conducted during the COVID-19 pandemic. Student social relationships based on friendship, perceived ability, and collaboration are characterized through a social network analysis. The methodology is quantitative and employs a one-group design. The sample consists of 196 students (142 males and 54 females) from different course sections. Strong and weak collaboration variables are defined based on whether or not interactions occur among friends. The results show a more intense collaboration in laboratory sessions than in theoretical lectures. Additionally, these variables show a low but positive Spearman correlation with grades, with the highest correlation observed between theory and laboratory grades. In conclusion, classroom collaboration enhances academic success that when encouraged can open new opportunities for teaching physics on virtual environments.