You are conducting an experiment inside a train car that may move along level rail tracks. a load is hung from the ceiling on a string. the load is not swinging, and the string is observed to make a constant angle of 45∘ with the horizontal. no other forces are acting on the load. which of the following statements are correct? check all that apply. 1 the train is an inertial frame of reference. 2 the train is not an inertial frame of reference. 3 the train may be instantaneously at rest. 4 the train may be moving at a constant speed in a straight line. 5 the train may be moving at a constant speed in a circle. 6 the train must be speeding up. 7 the train must be slowing down. 8 the train must be accelerating.