Question

3. Give reason of the following:

a) Speed is a scalar quantity.

b) Motion is categorised in different form

c) A shopkeeper uses standard weights for measurement,

d) Different units are used to measure different objects.​

Answer 1

Answer:

a.speed is a scalar quantity because it cannot be zero

Answer 2

Answer:

a) Speed is a scalar quantity because it can be represented by only magnitude and its meaning is understood. It does not need direction to be specified, as in case of velocity.

b) Various types of motions exist— translational motion, rectilinear motion, circular motion, etc. Thus by saying just motion, one cannot figure out the path traced by a body without specifying its type. Thus there are various types of motion.

c) A shopkeeper uses standard weights for measurement because if there would have been different types of weights in the market, one would get confused with the values, leading to chaos.

d) Units are chosen depending on the nature of the object to be measured. For example, the unit in which mass is measured cannot be used to measure distance, since both have no relation with each other. Thus, to avoid miscalculation, different units are used to measure different objects.

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