question_answer 1)

In which of the following examples of motion can the body be considered approximately a point object: (i) a railway carriage moving without jerks between two stations. (ii) a monkey sitting on the top of a man cycling smoothly on a circular track. (iii) a spinning cricket ball that turns sharply on hitting the ground, and (iv) tumbling beaker that has slipped off the edge of a table ?  

Answer:

(i) The carriage can be considered as the point object because the distance between two stations is much larger than the size of the carriage. (ii) The monkey can be considered as a point object because its size is much smaller than the distance covered by the cyclist. (iii) The spinning ball cannot be considered as point object because its size is quite appreciable as compared to the distance through which it turns on hitting the ground. (iv) The tumbling beaker slipping off the edge of a table cannot be considered a point object because its size is not negligibly smaller than the height of the table.