Assuming = 60 in Prob. 3.124, replace the two 40-lb forces with an equivalent force-couple system at D and determine whether the plumbers action tends to tighten or loosen the joint between (a) pipe CD and elbow D, (b) elbow D and pipe DE. Assume all threads to be right-handed. PROBLEM 3.124 In order to unscrew the tapped faucet A, a plumber uses two pipe wrenches as shown. By exerting a 40-lb force on each wrench, at a distance of 10 in. from the axis of the pipe and in a direction perpendicular to the pipe and to the wrench, he prevents the pipe from rotating, and thus avoids loosening or further tightening the joint between the pipe and the tapped elbow C. Determine (a) the angle that the wrench at A should form with the vertical if elbow C is not to rotate about the vertical, (b) the force-couple system at C equivalent to the two 40-lb forces when this condition is satisfied.

ENGR 232 Dynamic Engineering Systems Lecture 1 Introduction to Numerical Solutions with Differential Equations Dr. Michael Ryan Perspective Solutions to 1 Order ODEs • Analytically - Separation of variables– quantitative • Explicit solution Implicit Solution • Qualitative analysis ▯▯ • Sketch ▯▯, find EQ. Plot trajectories about EP • Direction field –Graphical technique to sketch solution curve versus time, grid spacing • Numerical Solution of DE • Euler’s methodRunge-Kutta etc. • Analog Computer - future lab(Simulink) Read Chapter1 and 18 of Schaum’s Outline ENGR 232 Spring14-15