Solved: Forces on an inclined plane An object on an

Chapter 11, Problem 74

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Forces on an inclined plane An object on an inclined plane does not slide provided the component of the objects weight parallel to the plane _Wpar _ is less than or equal to the magnitude of the opposing frictional force _Ff _. The magnitude of the frictional force, in turn, is proportional to the component of the objects weight perpendicular to the plane _Wperp _ (see figure). The constant of proportionality is the coefficient of static friction m 7 0. _Ff_ _ __Wperp_ Wpar Wperp Weight _ _ a. Suppose a 100-lb block rests on a plane that is tilted at an angle of u = 20 to the horizontal. Find _Wpar _ and _Wperp _. b. The condition for the block not sliding is _Wpar _ m_Wperp _. If m = 0.65, does the block slide? c. What is the critical angle above which the block slides with m = 0.65? 7