Q23 of 44 Page 8

. A function F(θ) is defined as

F (θ) = 1 – θ + - +


Why is it necessary for θ to be a dimensionless quantity?


In dimensional analysis, according to rule a physical quantity can be added or subtracted if and only if the physical quantities have same dimension.


For example, we can add 5 kg apple and 5 kg watermelon but cannot add 5 kg apple and 100 metre race because they have different dimensional unit.


Similarly, in the given question 1 has no unit and dimension. Therefore, θ should also not have any unit and dimension in order to be added with 1. Hence θ is a dimensionless quantity.


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Express unified atomic mass unit in kg.

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(a) The earth-moon distance is about 60 earth radius. What will be the diameter of the earth (approximately in degrees) as seen from the moon?

(b) Moon is seen to be of ( �)° diameter from the earth. What must be the relative size compared to the earth?


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