Overview:

This page will focus on the topic of Work:

Work- is the energy transferred by a force (when a force moves through a distance).

 

Work

When a force acts on an object and causes it a displacement, it is said that work has been done upon the object. There are three key ingredients to work - force, displacement, and cause. In order for a force to qualify as having done work on an object, there must be a displacement which is caused by the force in question. Everyday example include; a horse pulling a plough, a man pushing a trolley cart, an athlete launching a shot-put etc. In each case there is a force exerted upon an object to cause that object to be displaced.

Work done = force x distance moved in the direction of the force

WD = F xs

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Work Equation

Work can be described as:

W = F • d • cos Θ

The angle theta in the equation is associated with the amount of force that causes a displacement. When a force is exerted on an object at an angle to the horizontal, only a part of the force contributes to (or causes) a horizontal displacement. The horizontal component is found by multiplying the force F by the cosine of the angle between F and d. In this sense, the cosine theta in the work equation relates to the cause factor - it selects the portion of the force that actually causes a displacement.

Negative Work

Sometimes a force acts upon an object in a way that hinders displacement, an example includes a car skidding to a stop on a surface. In this case the force acts in the opposite direction to the motion of he object in order to slow it down. A situation like this involves what is known as negative work.

Units of Work 

One Joule is equivalent to one Newton of force causing a displacement of one meter. In other words,

The Joule is the unit of work.
 
1 Joule = 1 Newton * 1 meter
 
1 J = 1 N * m
Non-standard Units of Work:
foot•pound  kg•(m/s2)•m   kg•(m2/s2) 

In summary, work is done when a force acts upon an object to cause a displacement. Three quantities must be known in order to calculate the amount of work. Those three quantities are force, displacement and the angle between the force and the displacement.

 

Aiah Altayeb
3 May 2019 at 2:51

The information is well distributed throughout the page and it was understandable, however, some practice questions after each sub-topic could have been beneficial to the students to make sure that they understood each section. 

Frances Peterson
3 May 2019 at 23:29

Hi Ade,

I like how you divided each topic up into separate pages. It's so useful that you showed the derivation of many of the equations as this can be useful in exams. However, I also think you could have included practice questions on each page based on the topic of that page to ensure that students understand the information given.

Ahmed Hasnain
8 May 2019 at 21:29

It was a fantastic idea to add colour to your e-portfolio, i think this was a very clever feature to grab the attention of the reader to outline the important information which can help with retaining information for exams. However i did notice that there was two different font sizes used in this page which does not help with the flow of the text. 

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Updated on December 3, 2025; 119 page visits from 26 April 2019 to 15 December 2025