Question

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Why do we need standard unit measurement?
Give two examples each of modes of transport used on land, water and air.
In which of the following examples of motion, can the body be considered approximately a point object:

Answer 1

Answer:

1. We need standard unit for measurement to make our judgement more reliable and accurate. For proper dealing, measurement should be same for everybody. Thus there should be uniformity in measurement. For the sake of uniformity we need a common set of units of measurement, which are called standard units
2. Modes of Transport

(i) Land - Bus, truck, train.

(ii) Water - Ship, boat.

(iii) Air - Aeroplane, Helicopte

3. (a) 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.

(b) 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.

(c) The size of a spinning cricket ball is comparable to the distance through which it turns sharply on hitting the ground. Hence, the cricket ball cannot be considered as a point object.

(d) The size of a beaker is comparable to the height of the table from which it slipped. Hence, the beaker cannot be considered as a point object.