What is Work?

In classical physics terms, friend do work on an item when girlfriend exert a force on the object bring about it to move some distance. The lot of occupational you in reality do may have tiny relationship come the lot of effort you apply.

For example, if you press on a automobile stuck in a snow drift, you may exert a lot of of force (and effort) however if the vehicle does no budge, you have not done any kind of work! In stimulate for occupational to be excellent on one object, the object must move some distance as a an outcome of the force you apply. Over there are likewise constraints on the pressure you apply. Only force exerted in the very same direction together the motion of the object an outcome in work. You might think the you execute a many work if you lug an arm complete of publications from house to school. In truth you do no occupational at all! In carrying the ridge of books, girlfriend exert an upward force to hold the publications so castle don"t fall to the ground. There is no movement associated with this force. Together you walk, the motion of the books is horizontal not vertical. Because the force applied to the publications is vertical, and the activity is horizontal, you perform not do any kind of work top top the books.

Work is a move of power so occupational is excellent on things when friend transfer energy to that object. The amount of job-related done on an object depends ~ above the amount of pressure exerted ~ above the object and also the lot of street the object moves.

You are watching: Exert 100 j in 50 s and your power output is

Work = force x Distance

According to Newton"s 2nd Law the Motion, the net pressure on an object is dependence on the massive of the object, and also its acceleration during the movement.

Force = fixed x Acceleration

The usual unit of pressure is the Newton (N). One Newton is the pressure required to accelerate one kilogram of mass at 1 meter per 2nd per second.

1 N = 1kg m/s2

The quantity of occupational done to press a 10,000 N automobile a street of 10 meters rebab.netld certainly be

10,000 N x 10 m = 100,000 N m or 100,000 J

The Newton-meters room termed joules (J). The joule is named after James Prescott Joule (1818-1889) who an initial calculated the lot of electric work needed to develop a unit the heat. In his experiments, Joule found that the exact same amount of heat was developed by the very same amount of either electrical or mechanical job-related ("the mechanical equivalent of heat").

Learn more about work here.

What is Energy?

On march 10, 2005 sounding like an approaching locomotive, a tornado dropped out of billowing black clouds top top the new Zealand city of Greymouth. The winds hurled a truck into a lagoon, snapped strength poles in half, roofs cruised through the air and also buildings were ruined (go here to check out a video of this disaster).

Although wind is just moving air, it possesses energy. As soon as the wind moves the leaf on a tree or picks up and also hurls a truck, it has caused a change in the place of the object. Because of this it has done work. A measure of the capability to do job-related or cause change is called energy. Any type of time things does job-related on one more object, several of the energy of the functioning object is moved to the object increasing its power state. Choose work, the units of power are joules.

Energy is the lot of job-related a physical system is qualified of performing so power can be characterized as the which alters the position, physics composition or temperature of one object. There room two category of energy, kinetic energy and also potential energy. The difference in between them is whether the power is being moved (kinetic) or save on computer (potential). They are interconvertible.

Kinetic power is the energy of movement (the motion of waves, electrons, atoms, molecules) if potential power is stored power or energy of position that has the potential to do work-related (follow the kinetic and also potential energy links for a more in depth discussion). The kinetic power of an item is dependence both the fixed of the object and its velocity.

K.E. = 1/2 m v2

Thus a 3,000 lb vehicle moving at 50 mph will transfer much more kinetic energy than a 2,000 lb vehicle moving in ~ the very same rate. Energy can it is in stored in an object by lifting it up. The lot of potential energy rebab.netld it is in

P.E. = mgh

where m is the fixed of the object; h is the height of the object, and also g is the force of gravity acting on the object.

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This animation shows how energy converts in between kinetic and potential energy.

Animation courtesy of: http://www.bsharp.org/physics/stuff/swings.html

View exactly how kinetic and potential power are interrelated using a roller coaster demonstration.


A waterfall possesses both potential and kinetic energy. The water at the peak of the drops possesses potential energy. Together the water flows over the sheet of the falls, its energy is changed into kinetic energy.