# Work, energy and power

Dynamics allows us to calculate the acceleration of an object if we know the net force acting on it. From the acceleration, we can determine the velocity and from that, the position. If the force varies, this task becomes complicated.

Work and energy offers an alternative approach to the description of motion. In many cases, this description is simpler and more convenient than using Newton’s second law and the equations of kinematics. Furthermore, work and energy offer a more general framework for the characterisation of physical systems, which goes beyond the analysis of motion.

## Prerequisites

• the fundamental quantities of kinematics: position, displacement, velocity and acceleration;
• vectors v scalars;
• addition and subtraction of vectors;
• the scalar product (dot product) of vectors;
• Newton’s laws;
• the fundamentals of differential calculus (including integration).

## Learning objectives

By the end of this course, students will be able to

• interpret motion in the framework of work and energy;
• compute the work done by constant forces and variable forces;
• apply the work–kinetic energy theorem to predict the final state of mechanical processes;
• compare conservative and non-conservative forces;
• employ the concept of potential energy to simplify the calculations concerning certain mechanical processes;
• assess the power consumption of devices in the proper physical terms. 