Measurement and Significant Figures Quiz

Questions and Answers

What is the unit for a plane angle represented by?

steradian

degree

radian (correct)

arcsecond

Which of the following statements about solid angles is true?

The unit for solid angle is steradian. (correct)

Solid angle is measured in degrees.

Solid angle is represented by the symbol rad.

Solid angle is defined by the ratio of intercepted area to the cube of the radius.

What defines the SI unit of length, the metre?

It is based on the wavelength of a specific color of light.

It is equivalent to 100 centimeters.

It is defined by the dimensions of a physical object.

It is defined by the fixed numerical value of the speed of light. (correct)

Which of the following is incorrectly paired with its SI unit?

Time - minute (min) Signup and view all the answers

What is the purpose of using significant figures in scientific measurements?

To indicate the reliability and precision of a measurement. Signup and view all the answers

Which of the following is NOT a derived SI unit?

Metre (m) Signup and view all the answers

How is a steradian defined in relation to its radius?

It is the ratio of the intercepted area to the square of the radius. Signup and view all the answers

Why are angle measurements in radians considered dimensionless?

They relate to ratios of lengths, which cancel out units. Signup and view all the answers

What symbol represents the SI unit of time?

s Signup and view all the answers

What is the main characteristic of dimensionless quantities in the SI system?

They have no units attached to them. Signup and view all the answers

Study Notes

Significant Figures

Measurement results should reflect their precision; reported digits include both certain and uncertain figures.
Example: 287.5 cm has four significant figures where 2, 8, 7 are certain, and 5 is uncertain.
Reporting with excessive digits can mislead about measurement precision.

SI Derived Units

Special names are assigned to certain derived SI units.
SI units can utilize these specially named units alongside seven base units.
These concepts are further explained in referenced appendices.

Measurement Systems

Three primary systems of units:
- CGS (centimetre, gram, second)
- FPS (foot, pound, second)
- MKS (metre, kilogram, second)
The Système Internationale d'Unités (SI) is the internationally accepted system, revised in November 2018.

SI Base Units

There are seven base units in the SI system, which are essential for scientific measurement.
The definition of:
- Length: metre (m), based on the speed of light in a vacuum.
- Mass: kilogram (kg), based on the Planck constant.
- Time: second (s).

Additional Units

The SI includes two additional dimensionless units:
- Plane angle: radian (rad), defined as the ratio of arc length to radius.
- Solid angle: steradian (sr), defined as the ratio of the intercepted area to the square of the radius.

Conversions and Guidelines

SI uses a decimal system, making unit conversions straightforward.
Guidelines for significant figures and unit symbols are outlined to ensure clarity in measurements.
Changes in units do not affect the count of significant figures in measurements.

Description

Test your knowledge on significant figures, measurement systems, and SI units in this engaging quiz. Understand the importance of precision in measurements and the different systems of units used in scientific contexts. Challenge yourself with questions related to derived and base units as well.