Question

In which of the following examples of motion, can the body be considered approximately a point object:

• A. a railway carriage moving without jerks between two stations.
• B. a monkey sitting on top of a man cycling smoothly on a circular track.
• C. a spinning cricket ball that turns sharply on hitting the ground.
• D. a tumbling beaker that has slipped off the edge of a table.

Answer 1

Answer: (A), (B)

a railway carriage moving without jerks between two stations.

Answer 2

(a), (b)
The size of a carriage is very small as compared to the distance between two stations. Therefore, the carriage can be treated as a point sized object.
The size of a monkey is very small as compared to the size of a circular track. Therefore, the monkey can be considered as a point sized object on the track.
The size of a spinning cricket ball is comparable sharply on hitting the ground. Hence, the cricket ball cannot be considered as a point object.
The size of a beaker is comparable to the height of the table from which it slipped. Hence, the breaker cannot be considered as a point object.