# O: Engineering Engineering is an applied science, which uses an understanding of systems to design tools and engines that can assist mankind.

The IB Physics course contains two key sections at Standard Level:

• Rigid bodies and rotational dynamics (4 pages) - using the rotational equivalents to translational physical quantities to perform calculations for sprinng or rolling bodies
• Thermodynamics (4 pages) - defining the first and second laws of thermodynamics, representing gas changes on diagrams, and designing engines with net work done

• ### Torque and moment of inertia

Torque, also known as the moment of a force, is defined as the product of a force and the perpendicular distance from the line of action to the pivot.

• ### Equilibrium and angular acceleration

A body is in rotational equilibrium if the sum of the anticlockwise torques is equal to the sum of the clockwise torques about a pivot.

• ### Rotational dynamics

An object experiences angular acceleration if it is not in rotational equilibrium. The equations for linear motion have rotational equivalents.

• ### Angular momentum and rotational kinetic energy

The rotational equivalent of linear momentum is angular momentum. It is defined as the product of moment of inertia and angular velocity. We can also calculate rotational kinetic energy.

• ### First law

Thermodynamics is the study of the movement of heat and its relationship with work.

• ### Processes

We can use diagrams to show the processes that take place in a container of gas. A graph of pressure vs volume enables us to show all possible types of process.

• ### Second law

A heat engine converts thermal energy into mechanical work. The second law of thermodynamics can be expressed in three ways.

• ### Cyclic processes

A cyclic process is a series of transformations that take the gas back to its original state. These form a closed loop on a pV diagram.