College Physics with MasteringPhysics 7th Edition by Jerry Wilson,Anthony Buffa,Bo Lou

تمرين 122

Three horizontal forces (the only horizontal ones) act on a box sitting on a floor. One (call it F 1 ) acts due east and has a magnitude of 150 lb. A second force (call it F 2 ) has an easterly component of 30.0 lb and a southerly component of 40.0 lb. The box remains at rest. (Neglect friction.) (a) Sketch the two known forces on the box. In which quadrant is the unknown third force: (1) the first- quadrant; (2) the second quadrant; (3) the third quadrant; or (4) the fourth quadrant (b) Find the unknown third force in newtons and compare your answer to the sketched estimate.