Motion in a Straight Line – Solutions

1) In which of the following examples of motion, can 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 table.

Solution:

(a) In comparison to the size of the railway carriages, the distance between the two stations are very large, and hence, the carriage can be considered as a point object.

(b) If the cyclist describes a circular track of a very large radius, then the monkey can be considered as a point object, because in that case the distance covered by the cyclist is quite large as compared to the size of the monkey.