ENGR36_Tutorial_Flat_Friction_Spring-n-Wts.pptx 1 Bruce Mayer, PE Engineering-36: Engineering Mechanics - Statics Bruce Mayer, PE Licensed Electrical & Mechanical Engineer Engineering 25 Tutorial: Flat Friction

ENGR36_Tutorial_Flat_Friction_Spring-n-Wts.pptx 2 Bruce Mayer, PE Engineering-36: Engineering Mechanics - Statics Spring-n-Wts on Ramp  Two blocks A and B have a weight of 10 lb and 6 lb, respectively. They are resting on the incline for which the coefficients of static friction are µ A = 15% and µ B = 25%. Determine the incline angle for which both blocks begin to slide. Also find the required stretch or compression in the connecting spring for this to occur. The spring has a stiffness of k = 2 lb/ft.

ENGR36_Tutorial_Flat_Friction_Spring-n-Wts.pptx 3 Bruce Mayer, PE Engineering-36: Engineering Mechanics - Statics Conceptual Analysis  Since Block-A has the lower µ S value, it will Slide FIRST, thereby PULLING Block-B Down the ramp with it  Thus expect the Dual-Block Slip-Angle  Take the FBD of both Blocks noting that the Spring Force, F S, will be equal & opposite for both blocks

ENGR36_Tutorial_Flat_Friction_Spring-n-Wts.pptx 4 Bruce Mayer, PE Engineering-36: Engineering Mechanics - Statics

ENGR36_Tutorial_Flat_Friction_Spring-n-Wts.pptx 5 Bruce Mayer, PE Engineering-36: Engineering Mechanics - Statics

ENGR36_Tutorial_Flat_Friction_Spring-n-Wts.pptx 6 Bruce Mayer, PE Engineering-36: Engineering Mechanics - Statics

ENGR36_Tutorial_Flat_Friction_Spring-n-Wts.pptx 7 Bruce Mayer, PE Engineering-36: Engineering Mechanics - Statics