Units and Measurement

A set of flashcards based on the chapter on Units and Measurement, addressing key concepts, definitions, and rules related to physical quantities and their measurements.

What is a measurement of any physical quantity compared to?

A basic, arbitrarily chosen, internationally accepted reference standard called unit.

What are fundamental or base units?

The units for the fundamental or base quantities.

What is the system of units known as?

The complete set of both fundamental and derived units.

What is the SI unit of length?

Metre (m).

What is the SI unit of mass?

Kilogram (kg).

What does the SI system of units facilitate?

Simple and convenient conversions within the system, as it uses a decimal system.

What are the units for plane angle and solid angle in SI system?

Radian (rad) for plane angle and steradian (sr) for solid angle.

Which constant is used to define the SI unit of time?

The fixed numerical value of the caesium frequency ∆νcs.

How do significant figures indicate precision in measurement?

They include all known reliable digits plus the first uncertain digit.

What must be considered when calculating the final result of an operation involving significant figures?

The result cannot have more significant figures than the original values with the least significant figures.

What principle must hold true regarding dimensions in a mathematical equation?

Dimensions on both sides of the equation must be the same.

How can dimensional analysis be used in physics?

To check the dimensional consistency of equations and to deduce relations among physical quantities.

What happens if a measurement includes more digits than the significant digits?

It becomes misleading and gives a wrong idea about the precision of measurement.

What does the term 'significant figures' refer to?

The reliable digits plus the first uncertain digit in a measurement.

What is the key takeaway about dimensional consistency in an equation?

A dimensionally wrong equation must be wrong, but a dimensionally correct equation need not be right.

What is the significance of scientific notation in physical measurements?

It expresses measurements in powers of 10, indicating the precision of the values.

What does the dimensional formula of velocity look like?

L T–1.

What is a common method for deducing relations among physical quantities?

Using the method of dimensions, setting up the relationship as a product of dependent variables.

What should be done when combining measurements that include uncertainties?

Determine the error in the results based on the uncertainties from the original measurements.

What does the term 'derived units' refer to?

Units obtained from combinations of base units.

Which SI unit is used for luminous intensity?

Candela (cd).

What is a necessary condition for adding or subtracting physical quantities?

They must have the same dimensions.

What is an example of a dimensionless quantity?

The angle as the ratio of length to length.