Browse Definitions:
Definition

foot per second (ft/s or ft/sec)

The foot per second (symbolized ft/s or ft/sec) is the unit of linear speed in the foot-pound-second ( fps ) or English system. This quantity can be defined in either of two senses: average or instantaneous.

Average linear speed is obtained by measuring the distance in feet that an object travels in a certain number of seconds, and then dividing the distance by the time. If s avg represents the average speed of an object (in feet per second) during a time interval t (in seconds), and the distance traveled in that time is equal to d (in feet), then:

s avg = d / t

Instantaneous linear speed is more difficult to intuit, because it involves an expression of motion over an "infinitely short" interval of time. Let p represent a specific point in time. Suppose an object is in motion at about that time. The average speed can be measured over increasingly short time intervals centered at p , for example:

[ p -4, p +4]
[ p -3, p +3]
[ p -2 , p +2]
[ p -1, p +1]
[ p -0.5, p +0.5]
[ p -0.25, p +0.25]
.
.
.
[ p - x , p + x ]
.
.
.


where the added and subtracted numbers represent seconds. The instantaneous speed, s inst , is the limit of the measured average speed as x approaches zero. This is a theoretical value, because it cannot be obtained except by inference from measurements made over progressively shorter time spans.

It is important to realize that speed is not the same thing as velocity. Speed is a scalar (dimensionless) quantity, while velocity is a vector quantity consisting of speed and direction. We might say a car is traveling at 60 ft/s, and this tells us its speed. Or we might say the car is traveling at 60 ft/s at a compass bearing of 25 degrees (north-by-northeast); this tells us its velocity. As with speed, we might specify either the average velocity over a period of time, or the instantaneous velocity at an exact moment in time.

The foot per second is often used by lay people when talking about speed, particularly in the United States. But scientists, and most people in other parts of the world, use the meter per second (m/s), which is the standard unit of speed in the International System of Units ( SI ).

Also see foot , second , International System of Units ( SI ), and Table of Physical Units .

This was last updated in March 2011

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

  • 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.

  • audit program (audit plan)

    An audit program, also called an audit plan, is an action plan that documents what procedures an auditor will follow to validate ...

SearchSecurity

  • computer worm

    A computer worm is a type of malicious software program whose primary function is to infect other computers while remaining ...

  • 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 ...

SearchHealthIT

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

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

  • 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