PART A:
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 forces other than tension and gravity are acting on the load.

PART B:
Consider the train car described in the previous part. Another experiment is conducted in it: A net force of 20N is applied to an object of mass 5kg. Can you determine the acceleration of the object with respect to the train, and, if so, what is its value?