29 Questions
What is a unit in the context of measuring physical quantities?
A standard to compare with
Why do we need only a limited number of units to express all physical quantities?
Because units are derived from base units
What are the units for fundamental or base quantities called?
Fundamental units
What do we call the units obtained for physical quantities that are derived from base units?
Derived units
What is a complete set of base and derived units known as?
System of units
Why did scientists from different countries use different systems of units in the past?
Lack of a universally accepted system
What is the unit for plane angle?
Radian
Which SI unit represents mass?
Kilogram
How is the second defined in the SI system?
In terms of the caesium frequency
What is the symbol for the SI unit of electric current?
A
Which quantity has a dimensionless unit?
Plane angle
What represents the SI unit of length?
$m$
How many significant figures does the number 0.004700 km have?
4
What is the best way to remove ambiguities in determining the number of significant figures?
Reporting every measurement in scientific notation
In scientific notation, how is a number typically expressed?
a × 10^b (where a is between 1 and 10, and b is any positive or negative exponent of 10)
What happens to the number of significant figures when changing units in a measurement?
The significant figures remain the same
When rounding off a number in scientific notation, what value should 'a' be rounded to if 'a' is less than or equal to 5?
'a' should be rounded to 5
What are the base units for length, mass, and time in the MKS system?
Metre, kilogram, second
Which organization developed the standard scheme of symbols, units, and abbreviations for the SI system in 1971?
Bureau International des Poids et Measures
Why are conversions within the SI system considered simple and convenient?
Due to the use of the decimal system in SI units
In SI, how many base units are there according to Table 1.1?
Seven
What is the unit defined for plane angle dθ in SI?
Radians
How is solid angle dΩ defined in SI?
Ratio of intercepted area to square of radius
What is the rule provided for determining the significant figures when all zeros are between two non-zero digits?
All zeros are significant, regardless of the location of the decimal point.
If a number is less than 1, which zeros are not considered significant?
Zeros on the left of the first non-zero digit
In the number 0.06900, how many significant figures are there?
Four
What is the significance of the trailing zeros in a number with a decimal point?
They are always considered significant.
Why are the zeros in 4.700 m considered significant?
To indicate precision of measurement
How many significant figures does 123000 mm have?
Four
Learn about the SI units for plane angle (radian) and solid angle (steradian) which are both dimensionless quantities. Explore the definitions and symbols of radian (rad) and steradian (sr), along with other SI base quantities and units.
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