Work has long held a special place in our culture and in our lives. It’s where we learn important lessons that help us grow as people and as citizens, and it’s where many of the skills we use in our daily lives are learned. Work also helps us connect with others, which can make life more meaningful. It’s where we build relationships that shape who we are, and it’s often where our passions are found. It’s also where we get the energy that keeps us going, and the power to achieve our dreams.
However, not everything that is referred to as work is actually work in the scientific sense. In physics, work refers to the transfer of energy from one object to another through the application of force along a displacement. The amount of work that is done is equal to the product of the force exerted and the distance travelled, which is defined as a vector quantity (having a direction).
If the direction of the force is aligned with the displacement (such as when a ball falls from a table), the system’s energy increases meaning positive work was done. If the direction of the force is opposite to the displacement, such as when a roller coaster car is lifted by a chain, the system’s energy decreases meaning negative work was done.
The unit for measuring work is the joule, named after 19th-century English physicist James Prescott Joule. Since work is a form of energy, it can also be measured in other units including the newton-metre, erg, kilowatt hour, litre of water, or kilocalorie. It is also measured using a variety of nonstandard units, such as the foot-pound, the poundal, the btu, and the horsepower-hour.
We see examples of work all around us in our everyday lives. If a student puts a lot of effort into their homework, they’re doing work on it. A supermarket checkout attendant who lifts heavy baggage does work on it, as do the train station coolies who move baggage onto and off trains. However, if someone simply stands and holds on to a wall for a long time, this does not do work in the scientific sense because there is no movement of the mass of the object and no change in its acceleration or velocity.
To be considered work, there must be both a force and a displacement. The magnitude of the force must be greater than or equal to the magnitude of the displacement, and the force must be applied for a certain length of time. The physics of work is complex and includes many factors such as the laws of physics, thermodynamics, and fluid dynamics. For this reason, it is not always easy to determine whether or not an event is work in a particular circumstance. If you’re interested in learning more about the physics of work, we recommend checking out our article on The Principles of Work and The Laws of Work.