Describe los ejercicios que caliente las extremidades superiores del cuerpo

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this

the moving of the box is a result of centripetal force. think of that  as a car or a truck in this case creates a turn, the force of friction performing upon the turned wheels of the car runs centripetal force obligatory for circular motion for the things inside it.