The piston has a cross-sectional area, a, and the force pressure is force per volume area.

我们以活塞系统为例，来说明膨胀功。

麻省理工公开课 - 热力学与动力学课程节选

Carroll fluffed the opportunity but almost made amends moments later, stretching to get a foot on a teasing Wayne Routledge cross to force Forest skipper Camp into a diving save.

BBC: Sport - Football - Newcastle 2-0 Nottm Forest

Lt Comm Martin Lanni, Lt Michael Paulet, and Flt Lt Lee Turner all received the Air Force Cross for their role in the helicopter rescue of a group of climbers from Ben Nevis in May 2007.

BBC: UK soldiers honoured for bravery

They could be a force for cross-sectarian reconciliation, since many of the big tribal confederations, such as the Shammar, straddle the Sunni-Shia divide.

ECONOMIST: Iraq��s tribes may hold the balance of power