tatlc Friction 8 Fm\" ' I32 Sum of Forces Consider a block resting on a horizontal 8 Values surface. If you try to slide the block one way ~ l . V the surface will exert an opposing force in the Fwnea h '5 5'4\"\" +0 Cl Masses opposite direction. (This is in addition to the normal force exerted by the surface on the block.) This static frictional force will increase as the push increases until it starts moving. Empirically, it is found that the maximum static frictional force is proportional to the normal contact force between the block and the surface. That is, Wig \\NWM QSpeed \"@33ng Frletlon It foragipoviwnial mg f5,\" = #:n where the proportionality constant p, is called the coefficient of static friction Note: In the above diagram where the surface is horizontal and the applied force is horizontal, n = mg. This will not be the case if the applied force is directed upward or downward at an angle or if the surface is not horizontal. Box in mo+ion w some FKlCllON J? Is it true that the box begins to move as soon as you apply the force? 0 Homeboxwl notmovethehstantthattheforoelsapplled 0 Yes the box will begin to move the instant the force is applied. it disarm, . Is it true that the force of static friction acts in the same direction as the applied force? 0 There is not enough information 0 True they act in same direction 0 False they sometimes act in same dieetion 0 False they act In opposite Mon 0 False there is no x relation m How does the magnitude of the static friction change as you decrease the applied force? 0 First decreases and then increases CW) 0 Decreases What is the magnitude of the force of static friction as you apply the force? 0 Remains same $5 IWX= MS\" 0 Increases 0 None of the above What is the value of the net force (the Sum) as you applied the force to the box when the box is not moms? rm picture 0 .7