question_answer 4)

(i) Explain the statement clearly : To call a dimensional quantity 'large' or 'small' is meaningless without specifying a standard for comparison. (ii) In view of this, reframe the following statements, wherever necessary: (a) Atoms are very small objects (b) A jet plane moves with great speed (c) The mass of Jupiter is very large (d) The air inside this room contains a large number of molecules (e) A proton is much more massive than an electron (f) The speed of sound is much smaller than the speed of light.  

Answer:

(i) The given statement is correct. Measurement is basically a comparison process. Without specifying a standard of comparison, it is not possible to get an exact idea about the magnitude of a dimensional quantity. For example, the statement that the mass of the earth is very large, is meaningless. To correct it, we can say that the mass of the earth is large in comparison to any object lying on its surface. (ii) (a) The size of an atom is much smaller than even the sharp tip of a pin. (b) A jet planet moves with a speed greater than that of a superfast train. (c) The mass of Jupiter is very large compared to that of the earth. (d) The air inside this room contains more number of molecules than in one mole of air. (e) This is a correct statement. (f) This is a correct statement.