Units and Measurement 3

Question 1

What are significant measures

Answer 1

The result of a measurement is a number which includes digits that are relaibly known and an uncertain digit. The reliable digits plus the first digit which is uncertain is called siginificant figures.

Question 2

Why do we consider significant figures?

Answer 2

The reporting result of measurement that has more digits than significant figures is superfluous and is misleading about the precision of instrument

Question 3

what do significant figures indicate?

Answer 3

Significant figures indicate,
as already mentioned, the precision of
measurement which depends on the least count
of the measuring instrument. A choice of
change of different units does not change the
number of significant digits or figures in a
measurement.

Question 4

Rules for significant figures:

Answer 4

• All the non-zero digits are significant.
• All the zeros between two non-zero digits
  are significant, no matter where the
  decimal point is, if at all.
• If the number is less than 1, the zero(s)
  on the right of decimal point but to the
  left of the first non-zero digit are not
  significant. [In 0.00 2308, the underlined
  zeroes are not significant].
• The terminal or trailing zero(s) in a
  number without a decimal point are not
  significant.
• The trailing zero(s) in a number with a
  decimal point are significant.

Question 5

How do we represent scientific measurement to prevent trouble regarding trailing zeroes?

Answer 5

To remove ambiguities regarding trailing zeroes,determining the number of significant
figures, the best way is to report every
measurement in scientific notation (in the
power of 10). In this notation, every number is
expressed as a × 10b
, where a is a number
between 1 and 10, and b is any positive or
negative exponent (or power) of 10.

Question 6

what is the order of magnitude

Answer 6

the number can be
expressed approximately as 10b
in which the
exponent (or power) b of 10 is called order of
magnitude of the physical quantity.

Question 7

why do we round off the answers wrt arithmetic operations

Answer 7

The result of a calculation involving approximate
measured values of quantities (i.e. values with
limited number of significant figures) must reflect
the uncertainties in the original measured values.
It cannot be more accurate than the original
measured values themselves on which the result
is based. In general, the final result should not
have more significant figures than the original
data from which it was obtained.