MEASUREMENTS AND UNCERTAINTIES

Question 1

Provide the fundamental units and their respective SI units and symbols? (7)

Answer 1

• Time, Second (s)
• Distance, meter (m)
• Mass, kilogram (Kg)
• Current, Ampere (A)
• Temperature, Kelvin (K)
• Amount of Substance, moles (mol)
• Luminous intensity, Candela (Cd)

Question 2

Why is ‘s’ not appended with the units or the abbreviations?

Answer 2

to avoid confusion as ‘s’ could be mistaken for the S.I unit of time “s”

Question 3

In normalized scientific notation how are number written as?

Answer 3

m×10n
, where 1≤m<10
and n
is an integer

Question 4

What are the rules for determining the number of significant figures? (4)

Answer 4

• All non-zero digits and zeros between non-zero digits are significant
• All leading zeros are never significant
• If there is a decimal point all trailing zeros are significant
• When there is no decimal, all trailing zeros are not significant

Question 5

How are significant figures treated with calculations involving multiplication and division?

Answer 5

The product or quotient should have the same significant figures as the value with the least number of significant figures

Question 6

what are the rules with calculations involving both multiplication and division in the same answer?

Answer 6

• The values should not be rounded off until the calculation is done

Question 7

How are significant figures treated with calculations involving addition and subtraction?

Answer 7

• The answer should have the same significant figures as the value with the least number of decimal places.
• Example: 1.23 + 154.2
• The answer to this should have the same significant figures as the value 154.2