A joule, a term used in physics, is the kinetic energy of 1 kilogram moving at 1 meter per second. To examine what the definition of work means, let`s look at the other situations illustrated in Figure 1. For example, the person holding the briefcase in Figure 1b is not working. Here d = 0, i.e. W = 0. Why are you tired of just holding a load? The answer is that your muscles work against each other, but they don`t work on the system of interest (the “briefcase earth system” – see gravitational potential energy for more details). There must be movement for the work to be done, and there must be a component of force towards movement. For example, the person wearing the briefcase on flat ground in Figure 1c does not work on it because the force is perpendicular to the movement. That is, cos 90º = 0 and therefore W = 0. This is an example of work.

There is a force (gravity) acting on the book, causing it to descend (i.e. “fall”). In physics, work is defined as a force that causes the movement – or displacement – of an object. In the case of a constant force, the work is the scalar product of the force acting on an object and the displacement caused by this force. Although force and displacement are vector quantities, the work has no direction in vector mathematics due to the nature of a scalar product (or point product). This definition is consistent with the correct definition, since a constant force includes only the product of force and distance. Consider a spring exerting a horizontal force F = (−kx, 0, 0) proportional to its deviation in the direction x, regardless of how a body moves. The work of this spring on a body moving along the space with the curve X(t) = (x(t), y(t), z(t)) is calculated using its speed, v = (vx, vy, vz), to obtain example 1: A child pushes the chair forward and the chair falls backwards (not well balanced). Now the child`s labor is zero, because the chair is not advancing.

To do the work, the body/object must be moved along the direction of the force Example 2: Three people were working on a railway line and liked to move the iron bar over a distance of 1 meter. A force of 400 N is exerted by the three people, but the rod is not moved. What was the work of the three people? Answer: Zero reason: Since there is no displacement (the iron bar has not moved). Force X zero = 0 Answer: A sparrow sitting on a tree in the nest has no kinetic energy because it does not move. The lack of kinetic energy means that there is no movement of the body in the object. Therefore, the sparrow does not possess the ability to perform work in connection with the movement of the body. The work that W {displaystyle W} is performed by a gas body on its environment is: If a force acting on a body has a component in the direction of displacement, then the work done by the force is positive. Thus, when a body falls freely under the influence of gravity, the work of gravity is positive. The derivation of the principle of working energy begins with Newton`s second law of motion and the resulting force on a particle. The calculation of the scalar product of the forces with the velocity of the particle evaluates the instantaneous power added to the system. [18] If the force varies (for example, the compression of a spring), we must use the calculation to find the work done. If the force is given by F(x) (a function of x), then the work done by the force along the x-axis from a to b is: Formally, the work done on a system by a constant force is defined as the product of the component of the force in the direction of motion multiplied by the distance, by which force acts.

For unidirectional motions in one dimension, this is expressed as an equation as W = | Expressed. Q| (cosθ) |d|, where W is the work, d is the displacement of the system, and θ is the angle between the force vector F and the displacement vector d, as shown in Figure 1. We can also write this as W = Fd cos θ. In summary, work is done when a force acts on an object to cause displacement. Three quantities must be known to calculate the amount of work.