relativistic mass: meaning, definition, pronunciation and examples
C2Highly Technical / Academic
Quick answer
What does “relativistic mass” mean?
The apparent increase in the mass of an object as its velocity approaches the speed of light, a concept from Einstein's special theory of relativity.
Audio
Pronunciation
Definition
Meaning and Definition
The apparent increase in the mass of an object as its velocity approaches the speed of light, a concept from Einstein's special theory of relativity.
A relativistic concept defining mass as dependent on the object's velocity relative to the observer, in contrast to invariant rest mass. While used historically in physics education and popular science, it is largely superseded in modern physics by the concept of relativistic momentum and invariant mass.
Dialectal Variation
British vs American Usage
Differences
No significant difference in usage between British and American English for this technical term.
Connotations
Identically technical in both variants.
Frequency
Equally rare and specialised in both varieties, confined to physics discourse.
Grammar
How to Use “relativistic mass” in a Sentence
The relativistic mass of [NOUN PHRASE] increases as...[NOUN PHRASE] has a relativistic mass given by...According to relativity, [NOUN PHRASE]'s relativistic mass is...Vocabulary
Collocations
Examples
Examples of “relativistic mass” in a Sentence
verb
British English
- [No verbal use for this noun phrase]
American English
- [No verbal use for this noun phrase]
adverb
British English
- [No adverbial use for this noun phrase]
American English
- [No adverbial use for this noun phrase]
adjective
British English
- The relativistic-mass increase is negligible at everyday speeds.
American English
- The relativistic-mass effect must be accounted for in the cyclotron design.
Usage
Meaning in Context
Business
Not used.
Academic
Used in physics textbooks, lectures, and historical discussions of special relativity.
Everyday
Not used.
Technical
Used in physics and engineering contexts involving high-velocity particles (e.g., particle accelerators).
Vocabulary
Synonyms of “relativistic mass”
Strong
Neutral
Weak
Vocabulary
Antonyms of “relativistic mass”
Watch out
Common Mistakes When Using “relativistic mass”
- Using 'relativistic mass' interchangeably with 'rest mass'.
- Applying the concept outside of relativistic speeds.
- Thinking the object physically gains matter.
FAQ
Frequently Asked Questions
It is a real mathematical consequence of special relativity, but it is a frame-dependent quantity. Modern physics emphasises invariant ('rest') mass as the fundamental property.
No, they do not gain new matter. Their resistance to acceleration (inertia) increases from the perspective of a stationary observer, which is mathematically described as an increase in relativistic mass.
Mostly in historical contexts, some educational settings, and pop-science explanations. Professional physics typically uses the concepts of relativistic momentum and invariant mass.
The effects become noticeable (above 1% change) at speeds greater than about 10% of the speed of light (approximately 30,000 km/s).
The apparent increase in the mass of an object as its velocity approaches the speed of light, a concept from Einstein's special theory of relativity.
Relativistic mass is usually highly technical / academic in register.
Relativistic mass: in British English it is pronounced /ˌrel.ə.tɪˈvɪs.tɪk mæs/, and in American English it is pronounced /ˌrel.ə.t̬əˈvɪs.tɪk mæs/. Tap the audio buttons above to hear it.
Phrases
Idioms & Phrases
- “[No common idioms for this highly technical term]”
Learning
Memory Aids
Mnemonic
Think 'RELATIVE' + 'MASS'. Mass that is not fixed but RELATIVE to your speed. As you go faster, your resistance to acceleration (mass) RELATIVELY increases.
Conceptual Metaphor
MASS IS RESISTANCE TO MOTION. As an object's speed increases, its 'struggle' to go faster (its resistance) grows immensely, metaphorically 'gaining weight'.
Practice
Quiz
What is the primary reason modern physics often avoids the term 'relativistic mass'?