1. ENGR 104: Intro to Engineering Lab Different Strokes-Golf Analysis Instructors: Dr. Binh Q. Tran Dr. Otto C. Wilson, Jr. © 2002-09 The Catholic University of America Dept of Biomedical Engineering

2. ENGR 104: Intro to Engineering Lab Dept of Biomedical Engineering, Catholic University Lab Goals & Objective n The objective of this lab is to study the influence of friction on a moving body. n Students will design, develop, and perform lab experiments to compute frictional coefficients,  f, on various surfaces.

3. ENGR 104: Intro to Engineering Lab Dept of Biomedical Engineering, Catholic University How can we model the friction problem? n Free-body diagram ???

4. ENGR 104: Intro to Engineering Lab Dept of Biomedical Engineering, Catholic University Free-Body Diagram W=mg F x =ma x Ff=fWFf=fW Free Body DiagramPhysical System

5. ENGR 104: Intro to Engineering Lab Dept of Biomedical Engineering, Catholic University Kinematics n Vector forms: –Displacement:x = ix + jy –Velocity: v = iv x + jv y –Acceleration:a = ia x + jv y n Recall from Projectile Motion Lecture: v xf 2 = v xo 2 + 2a x *(x f - x o ) n If v xf = 0 (i.e. ball comes to stop), 0 = v xo 2 + 2a x *(x f - x o ) x f = - v xo 2 / 2a x (1)

6. ENGR 104: Intro to Engineering Lab Dept of Biomedical Engineering, Catholic University Newton’s Laws n Newton’s 3 rd Law: F x + F f = 0or F x = - F f F x = m * a x -F f = -  f * W  a x = -  f *g(2) n thus, combine (1) & (2): x f = v xo 2 / 2g  f

7. ENGR 104: Intro to Engineering Lab Dept of Biomedical Engineering, Catholic University Labview Interface n Develop Labview to compute velocity of the ball. –VI only gives times at leading & trailing edge of pulse. –Need to write code to compute velocity & compute friction coefficient