Editing Work (physics) (section)

==Work and energy==
The work {{mvar|W}} done by a constant force of magnitude {{mvar|F}} on a point that moves a displacement {{mvar|s}} in a straight line in the direction of the force is the product
<math display="block"> W = \mathbf{F} \cdot \mathbf{s}
</math>

For example, if a force of 10 newtons ({{math|1=''F'' = 10 N}}) acts along a point that travels 2 metres ({{math|1=''s'' = 2 m}}), then {{math|1=''W'' = ''Fs'' = (10 N) (2 m) = 20 J}}. This is approximately the work done lifting a 1&nbsp;kg object from ground level to over a person's head against the force of gravity.

The work is doubled either by lifting twice the weight the same distance or by lifting the same weight twice the distance.

Work is closely related to [[energy]]. Energy shares the same unit of measurement with work (Joules) because the energy from the object doing work is transferred to the other objects it interacts with when work is being done.<ref name=":0" /> The work–energy principle states that an increase in the kinetic energy of a [[rigid body]] is caused by an equal amount of positive work done on the body by the resultant force acting on that body. Conversely, a decrease in kinetic energy is caused by an equal amount of negative work done by the resultant force. Thus, if the net work is positive, then the particle's kinetic energy increases by the amount of the work. If the net work done is negative, then the particle's kinetic energy decreases by the amount of work.<ref name="walker">{{cite book |last1=Walker |first1=Jearl |last2=Halliday |first2=David |last3=Resnick |first3=Robert |title=Fundamentals of physics |date=2011 |publisher=Wiley |location=Hoboken, NJ |isbn=9780470469118 |pages=154 |edition=9th}}</ref>

From [[Newton's laws of motion|Newton's second law]], it can be shown that work on a free (no fields), rigid (no internal degrees of freedom) body, is equal to the change in kinetic energy {{math|''E''<sub>k</sub>}} corresponding to the linear velocity and [[angular velocity]] of that body,
<math display="block"> W = \Delta E_\text{k}.</math>
The work of forces generated by a potential function is known as [[potential energy]] and the forces are said to be [[Conservative force|conservative]]. Therefore, work on an object that is merely displaced in a conservative force [[Field (physics)|field]], without change in velocity or rotation, is equal to ''minus'' the change of potential energy {{math|''E''<sub>p</sub>}} of the object,
<math display="block"> W = -\Delta E_\text{p}.</math>
These formulas show that work is the energy associated with the action of a force, so work subsequently possesses the [[Dimensional analysis|physical dimensions]], and units, of energy.
The work/energy principles discussed here are identical to electric work/energy principles.