Project-based learning, such as model eliciting activities (MEAs), enhances student understanding and problem solving in the engineering classroom, but its effect on student motivation is less understood. Therefore, this objective of this work was to determine if the use of a MEA versus traditional homework in a biomechanics classroom would enhance student intrinsic motivation. A MEA based on designing a simplified hip replacement prosthesis was developed and implemented in an introductory biomechanics classroom consisting of 2nd and 3rd year bioengineering students. After introducing the problem, students defined important assumptions, equations, and parameters for their simplified hip implant. After reviewing the necessary assumptions and equations, students modeled a hip implant by implementing basic static equilibrium and strength of materials equations in Microsoft Excel and wrote a memo to communicate their results. After submission of the project, students filled out a post-activity questionnaire online (Qualtrics) to survey their motivation. Questions were designed to assess motivation based on competence, autonomy, purpose, community, and appreciation for both the MEA and traditional homework using a Likert scale (12 questions each). Additionally, students ranked five items representing autonomy, community, purpose, competence, and extrinsic forms of motivation in order of importance. Survey data was analyzed using a Wilcoxon Signed Rank test to compare average responses between the MEA and homework (significance at p < 0.05), and a Friedman ANOVA was used to compare student rankings with a post-hoc Wilcoxon Signed Rank test using Bonferroni correction (significance at p < 0.005). Correlations between question scores were made using Kendall's Tau-b. Of the 12 questions on the questionnaire, 3 were significantly different between the MEA and homework. Specifically, students found the MEA to be more frustrating, had more choice in how to complete the MEA, and felt the MEA better related to their career goals. When ranking items, competence, purpose, and extrinsic motivation were ranked significantly higher compared to community and autonomy. Correlations indicated that students enjoyed the project more when they learned the content (τ = 0.61), that students who felt the MEA helped with problem solving skills saw more "real world" application (τ = 0.61), and that students who felt the MEA helped them learn the content also best understood the expectations for the project (τ = 0.54). Although students found the MEA to be more frustrating than traditional homework, they also felt they had more choice in how to complete the assignment (i.e. autonomy) and that it was more related to their career goals (i.e. purpose). Generally, 2nd year students desired less autonomy and were more frustrated than 3rd year students. Students responded that the least important motivators to them were autonomy and community, and so future iterations of the activity should target student competence and purpose. Overall, students showed higher motivation in key areas for the MEA compared to traditional homework, and therefore strategic implementation of MEAs to study biomechanics may assist to both improve student understanding and enhance motivation. [ABSTRACT FROM AUTHOR]