Friction, force that resists the sliding or rolling of one solid object over another. Frictional forces provide the traction needed to walk without slipping, but they also present a great measure of opposition to motion. Types of friction include kinetic friction, static friction, and rolling friction. Frictional force versus applied force 1, 8. The slight fluctuations in the kinetic region of the plot are due to the slight dependency of µk on the speed of the object 8. Figure 3: Plot of frictional force versus applied force Table 1 lists the coefficients of static and kinetic friction for various object/surface combinations 5, 8.

/ ˈfrɪk ʃə nl /


moved, worked, or produced by friction.



If your language skills aren’t already top-notch, then this vocab quiz can get you up to speed!

Origin offrictional



Words nearby frictional

fricative, Frick, fricking, FRICS, friction, frictional, frictional soil, frictional unemployment, friction clutch, friction drive, friction gearing UnabridgedBased on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for frictional

  • There it becomes an effort tending either to move A upon B, or to move the body B itself, according to the frictional conditions.

    Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 2Various
  • There was a sense of electric surcharge everywhere, frictional, a neurasthenic haste for excitement.

  • Frictional Electricity is that produced by the friction of one substance against another.

    Hawkins Electrical Guide, Number OneNehemiah Hawkins
  • He conceived of the air giving a frictional force to an object in motion.

  • When man first began experimenting, he produced a current by frictional means, and collected the electricity in a bottle or jar.

Genre(s)Survival horror
Developer(s)Frictional Games
Publisher(s)Paradox Interactive
Lexicon Entertainment
Writer(s)Thomas Grip, Jens Nilsson, Tom Jubert
Composer(s)Mikko Tarmia
First releasePenumbra: Overture
30 March 2007
Latest releasePenumbra: Requiem
27 August 2008

Penumbra is an episodicsurvival horror video game series developed by Frictional Games and published by Paradox Interactive and Lexicon Entertainment. The games use the HPL Engine 1, initially developed as a tech demo. Penumbra is notable for its horror styling and for allowing advanced physical interaction with the game environment.[1]

Main series[edit]

Penumbra: Overture (2007)[edit]

Set in the year 2001, Penumbra: Overture follows the story of Philip, a thirty-year-old physicist whose mother recently died. After receiving a mysterious letter from his supposedly dead father, Philip follows a series of clues that lead him to a mysterious location in uninhabited northern Greenland.

Penumbra: Black Plague (2008)[edit]

The story of Black PlagueMail merge toolkit cracked version downloads. begins as an email sent by Philip to a friend, explaining what has happened to him and begging him to finish the work he could not. The rest of the game then proceeds as a flashback narrated by Philip to his friend in the email, beginning from where the previous game left off.

Penumbra: Requiem (2008)[edit]

A puzzle expansion with nine levels for the Black Plague Gold Edition. The game starts as the last one ends, with Phillip sending the 'kill them all' message. As soon as he finishes, one of the Infected barges in and hits Phillip on the head with something unseen.

Penumbra (Tech Demo)[edit]

Frictional Collection Steam

The Penumbra series is based on Frictional Games' earlier game 'Penumbra Tech Demo', a short tech demo meant to demonstrate the capabilities of the company's HPL Engine 1. The developers admitted that they edited the original engine which was 2D to support 3D environments.



  1. ^Interview With Frictional Games – Amnesia Linux Gaming News, 25 November 2009 (Article by Maxim Bardin)

External links[edit]

Frictional Collection Definition

Wikiquote has quotations related to: Penumbra (video game series)
Retrieved from ''