Difference between revisions of "Work"
DavidB4-bot (talk | contribs) (clean up & uniformity) |
m (Formatting) |
||
| Line 1: | Line 1: | ||
In [[physics]], '''work''' refers to the [[dot product]] of [[force]] and [[distance]] vectors | In [[physics]], '''work''' refers to the [[dot product]] of [[force]] and [[distance]] vectors | ||
.<ref>Serway and Beichner, ''Physics for Scientists and Engineers'', Fifth Edition</ref> | .<ref>Serway and Beichner, ''Physics for Scientists and Engineers'', Fifth Edition</ref> | ||
| − | |||
| − | |||
<math>W = \bold{F} \cdot \bold{d}</math> | <math>W = \bold{F} \cdot \bold{d}</math> | ||
| − | |||
| − | |||
Or: | Or: | ||
<math>W = Fd \cos\theta</math> | <math>W = Fd \cos\theta</math> | ||
| − | |||
| − | |||
Where θ is the angle that separates the vectors. The second form of the equation is the expanded form of the "dot product" in the first equation. In physics, the dot product "a · b" (read "a dot b") can be rewritten as "|a| |b| cos θ". | Where θ is the angle that separates the vectors. The second form of the equation is the expanded form of the "dot product" in the first equation. In physics, the dot product "a · b" (read "a dot b") can be rewritten as "|a| |b| cos θ". | ||
| Line 19: | Line 13: | ||
<math>\int \bold{F} \cdot \mathrm{d}\bold{s}</math> | <math>\int \bold{F} \cdot \mathrm{d}\bold{s}</math> | ||
| − | |||
| − | |||
Work is a transfer of [[energy]]; if ''W'' is positive, there is a transfer of energy ''to'' the system, and if ''W'' is negative there is a transfer of energy ''from'' the system. | Work is a transfer of [[energy]]; if ''W'' is positive, there is a transfer of energy ''to'' the system, and if ''W'' is negative there is a transfer of energy ''from'' the system. | ||
Revision as of 19:44, September 7, 2016
In physics, work refers to the dot product of force and distance vectors .[1]
<math>W = \bold{F} \cdot \bold{d}</math>
Or:
<math>W = Fd \cos\theta</math>
Where θ is the angle that separates the vectors. The second form of the equation is the expanded form of the "dot product" in the first equation. In physics, the dot product "a · b" (read "a dot b") can be rewritten as "|a| |b| cos θ".
When the force is not constant, the correct expression uses integration:
<math>\int \bold{F} \cdot \mathrm{d}\bold{s}</math>
Work is a transfer of energy; if W is positive, there is a transfer of energy to the system, and if W is negative there is a transfer of energy from the system.
Its units are that of force multiplied by distance, in SI this is Newton · Meter, or Joule. The aberrant unit kWh (kilowatt-hour) is sometimes used; this unit is the product of kilowatt, or 1,000 Watts (Joules per second), and hour, or 3,600 seconds.
References
- ↑ Serway and Beichner, Physics for Scientists and Engineers, Fifth Edition