If the external world does work on the system, the quantity of work is negative.
Is negative right or is it positive?
If you are writing the system equations, the work done by external forces will be a + number, indicating an increase of energy to the system.
To determine the sign of work done by the external world on a system, we need to understand the definition of work. Work is defined as the application of a force over a displacement, given by the equation W = F * d * cos(theta), where W is the work done, F is the applied force, d is the displacement, and theta is the angle between the force and the displacement vectors.
If the applied force and the displacement have opposite directions (theta = 180 degrees), the work done would be negative. This indicates that the external world is doing work on the system, resulting in a decrease in the system's energy.
Conversely, if the applied force and the displacement have the same direction (theta = 0 degrees), the work done would be positive. This indicates that the external world is adding energy to the system.
Therefore, if the external world does work on the system and the quantity of work is negative, it means that the external forces are doing work on the system, resulting in a decrease in the system's energy.