What Is Work?

In physics, work is the transfer of energy from one object to another. It is the product of force times displacement, and it is measured in SI units (Newton-meters). The same equation is used to calculate energy, which is a broader concept that includes potential and kinetic energy as well as other forms of energy like rest mass energy, thermal energy, and pressure energy.

In everyday life, there are many examples of work: a horse pulling a plow through the field, a father pushing his child’s cart down the grocery store aisle, a freshman lifting her backpack full of books onto her shoulder, a weightlifter performing a lift, and an Olympian launching the shot-put. The important thing to remember is that there are three key ingredients in work: a force, a displacement, and a cause. The force must push or pull to do work on the object, and it must change the state of the object – the force must cause the displacement.

If the force is parallel to the displacement, then no work has been done. However, if the force is perpendicular to the displacement, then some work has been done. It is also possible for an object to move in a circular motion without changing its linear or angular velocity – in this case the centripetal force exerted on the object must be equal and opposite to the radius of the circle, so that it does no work.

Similarly, if an object is not moving in a particular direction, then the force that caused the motion must be constant. This means that the amount of work that was done is a negative quantity (-Delta Etextk). Work must be done to an object to change its state, so it cannot be done to an empty (or inactive) object.

In general, the work done by a point-force on a curve X is given by a line integral of the vectors F, v, and dx, where dx represents the distance the point moves along the curve – in other words, its acceleration. This integral is the same as the result obtained by multiplying the forces acting at each point of the curve, and it is therefore very easy to determine the net force on the curve at any time t. This is known as the Work-energy Theorem. One common unit of work is the joule, which has the symbol J. It is defined as 1 newton-meter (Nm) per kilogram of acceleration (m2/s2). Other measurement units that are often used for work include the erg, foot-pound, kilojoule, and watt-hour. However, these are not the only units of measurement that can be used; sometimes other units that are typically reserved for heat and energy content are used – for example, the therm, BTU, and calorie. This is because work can be considered a type of energy, and everything that has energy has the potential to do work. This is a fundamental principle of the universe.