Students' responses to energy & momentum (EM) concepts were investigated. EM concepts are fundamental and crosscutting in physics. A standardized Energy and Momentum Conceptual Survey (EMCS) test were used to collect quantitative data from 108 first year science students enrolled in a university in Ethiopia. Concentration analysis was used to analyze the responses in terms of concentration score, concentration factor, and concentration deviation. A one-sample t-test was conducted and showed no statistically significant difference (t=0.33, p=0.74) between the average concentration score and the hypothetical random score. A paired-samples t-test was conducted and showed also a no statistically significant difference (t=1.25, p=0.22) between the concentrations of students' responses to the scientific conceptions and misconceptions. The results showed that newly enrolled university science students have low, random and inconsistent conceptual knowledge of core physics concepts. Concentration analysis is recommended for science teachers to diagnose students' level of understanding before instruction.