system of units


Q1.   Calculate the number of light  years in one metre.

Q2.   The mass of an electron is 9.11kg.How many electrons would make 1 kg ?

Q3.    In defining the standard of length, we have to specify the temperature at which the    measurement  should be made. Are we justified in calling length a fundamental quantity, if another physical quantity (temperature) has to be specified in choosing a standard ?

Q4.    Which type of phenomenon can be used as a measure of time ? Give three examples.

Q5.    Why has ‘second’ been defined in terms of periods of radiation from Cesium -133 ?

Q6      Derive the S.I unit of joule (J) in terms of fundamental units.

Q7.     What is a coherent system of units ?

Q8.     Do AU and A represent the same unit of length ?

Q9.     Does magnitude of a quantity change with change in the system of units ?

Q10.   Can a body have zero mass and zero weight ?

Q11.   Name two types of mass ?

Q12.   Is light year a of time ?

Q13.    Why is the cylinder used in defining kg made of platinum iridium alloy ?

Q14.     What is common between bar and torr ?