Browse Definitions:
Definition

momentum

Momentum is a vector quantity that is the product of the mass and the velocity of an object or particle. The standard unit of momentum magnitude is the kilogram-meter per second (kg · m/s or kg · m · s -1 ). Alternatively, the gram-centimeter per second (g · cm/s or g · cm · s -1 ) can be used to express momentum magnitude. The direction of a momentum vector can be expressed in various ways, depending on the number of dimensions involved, and is the same as the direction of the velocity vector.

Momentum, like velocity, is relative. Consider a 1,000-kg car moving at 20 m/s with respect to the surface of a highway, traveling northward. If you are driving the car, the momentum of the car relative to your body is zero. If you stand by the side of the road, the momentum of the car relative to you is 20,000 kg · m/s northward.

If you are driving a 1,000-kg car at 15 m/s with respect to the road and are traveling northward, and a truck of mass 1,500 kg is moving 20 m/s with respect to the road and comes up behind you in the same direction, the truck's momentum relative to you is the product of its relative velocity (5 m/s northward) and its mass (1,500 kg), or 7,500 kg · m/s northward. Relative to the truck, the momentum of your car will be in the opposite direction, and will be smaller: 5 m/s x 1,000 kg = 5,000 kg · m/s southward. Thus, if a collision occurs, the danger is greater to the object that is less massive.

If the above mentioned truck passes you going the opposite way on the road, its momentum relative to you is 35 m/s x 1,500 kg southward, or 52,500 kg · m/s southward. Relative to it, your momentum is 35 m/s x 1,000 kg northward, or 35,000 kg · m/s northward. In that situation, as with the rear-end scenario, the peril is greater to the less massive vehicle in the event of a collision.

Momentum, like velocity, can be expressed either as an average over a period of time or as an instantaneous value at a single moment in time.

Also see mass , velocity , vector , SI (International System of Units), and Table of Physical Units .

This was last updated in September 2005

Start the conversation

Send me notifications when other members comment.

By submitting you agree to receive email from TechTarget and its partners. If you reside outside of the United States, you consent to having your personal data transferred to and processed in the United States. Privacy

Please create a username to comment.

-ADS BY GOOGLE

File Extensions and File Formats

Powered by:

SearchCompliance

  • internal audit (IA)

    An internal audit (IA) is an organizational initiative to monitor and analyze its own business operations in order to determine ...

  • pure risk (absolute risk)

    Pure risk, also called absolute risk, is a category of threat that is beyond human control and has only one possible outcome if ...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

SearchSecurity

  • computer exploit

    A computer exploit, or exploit, is an attack on a computer system, especially one that takes advantage of a particular ...

  • cyberwarfare

    Cyberwarfare is computer- or network-based conflict involving politically motivated attacks by a nation-state on another ...

  • insider threat

    Insider threat is a generic term for a threat to an organization's security or data that comes from within.

SearchHealthIT

SearchDisasterRecovery

  • business continuity and disaster recovery (BCDR)

    Business continuity and disaster recovery (BCDR) are closely related practices that describe an organization's preparation for ...

  • business continuity plan (BCP)

    A business continuity plan (BCP) is a document that consists of the critical information an organization needs to continue ...

  • call tree

    A call tree -- sometimes referred to as a phone tree -- is a telecommunications chain for notifying specific individuals of an ...

SearchStorage

SearchSolidStateStorage

  • 3D XPoint

    3D XPoint is memory storage technology jointly developed by Intel and Micron Technology Inc.

  • RRAM or ReRAM (resistive RAM)

    RRAM or ReRAM (resistive random access memory) is a form of nonvolatile storage that operates by changing the resistance of a ...

  • JEDEC

    JEDEC is a global industry group that develops open standards for microelectronics.

SearchCloudStorage

  • Google Cloud Storage

    Google Cloud Storage is an enterprise public cloud storage platform that can house large unstructured data sets.

  • RESTful API

    A RESTful application program interface breaks down a transaction to create a series of small modules, each of which addresses an...

  • cloud storage infrastructure

    Cloud storage infrastructure is the hardware and software framework that supports the computing requirements of a private or ...

Close