Question

70. A pencil rests against a corner, as shown below. The sharpened end of the pencil touches a smooth vertical surface and the eraser end touches a rough horizontal floor. The coefficient of static friction between the eraser and the floor is ug = 0.80. The center of mass of the pencil is located 9.0 cm from the tip of the eraser and 11.0 cm from the tip of the pencil lead. Find the minimum angle e for which the pencil does not slip. 11.0 cm - 9.0 cm

Edited***
Change the location of the center of mass to 7cm from the eraser and change the distance of the center of mass from the pencils lead tip to be 13.2cm. Finally, assume that the coefficient of friction 0.7. Solve for the minimum angle such that the pencil wont slip. Enter answer in degrees.

Answer 1

اے باM Balancing torque about floor point, NE {T=-(7cm) (mg) caso +((7+19.2) Nu sino) = 0 7 mg caso = 20.2 Nw sind No= 0.3465 mg tand Efx = f-Nw=o a f= No {fy = No - mg=0 & Ne = mg 4f 0.3465 - 07 10: 26.30 5.3465 - 6.2 4 - tand