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

SearchCompliance

SearchSecurity

  • black hat

    Black hat refers to a hacker who breaks into a computer system or network with malicious intent.

  • copyright

    Copyright is a legal term describing ownership of control of the rights to the use and distribution of certain works of creative ...

  • keylogger (keystroke logger or system monitor)

    A keylogger, sometimes called a keystroke logger or system monitor, is a type of surveillance technology used to monitor and ...

SearchHealthIT

  • population health management (PHM)

    Population health management (PHM) is a discipline within the healthcare industry that studies and facilitates care delivery ...

  • ICD-10-PCS

    The International Classification of Diseases, 10th Revision, Procedure Coding System (ICD-10-PCS) is a U.S. cataloging system for...

  • U.S. National Library of Medicine (NLM)

    The U.S. National Library of Medicine (NLM) is the largest biomedical library in the world.

SearchDisasterRecovery

  • 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 ...

  • mass notification system (MNS)

    A mass notification system is a platform that sends one-way messages to inform employees and the public of an emergency.

SearchStorage

  • hybrid hard drive (HHD)

    A hybrid hard drive (HHD), sometimes known as a solid-state hybrid drive (SSHD), is a mass storage device that combines a ...

  • USB flash drive

    A USB flash drive -- also known as a stick, thumb or pen drive -- is a plug-and-play portable storage device that uses flash ...

  • open source storage

    Open source storage is data storage software developed in a public, collaborative manner that permits the free use, distribution ...

SearchSolidStateStorage

  • 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.

  • M.2 SSD

    An M.2 SSD is a solid-state drive (SSD) that conforms to a computer industry specification written for internally mounted storage...

SearchCloudStorage

  • 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 ...

  • Zadara VPSA and ZIOS

    Zadara Storage provides block, file or object storage with varying levels of compute and capacity through its ZIOS and VPSA ...

Close