C) Calculate the reaction at the pivot when the counter weight is 2350N and the other end of the boom is supported

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

your answer is, orbit around the nucleus

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.