## 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.

## Make Your Own Quizzes and Flashcards

Convert your notes into interactive study material.

Get started for free