PHYSICS · Single correct · A Level · Physics · Measurements and their errors · Measurements and their errors
Problem
Two laboratories measure the same rod. Laboratory X reports its length as “1.000m” while Laboratory Y reports “39.37in”. Which of the following is the best explanation for why only Laboratory X’s statement can be directly used in an international scientific paper?
(a) Because inches differ slightly among imperial standards, a value reported in inches cannot be reproduced exactly worldwide.
(b) Since 1.000 has more significant figures than 39.37, the metre reading is inherently more precise and therefore acceptable.
(c) The metre is an SI base unit with an internationally fixed definition, whereas the inch is non-SI and not the preferred unit in scientific communication.
(d) An inch is defined only as a fraction of a foot, so this secondary unit cannot be used to report a fundamental measurement like length.