Engineering Physics

Engineering physics is the area of engineering that concerns the practical application of physics to industry, science, and technology.

Areas covered by engineering physics

Engineering physics includes everything from biology to maths and technology. Exploring several examples, we will see why physics plays an important role in solving engineering problems. Areas related to engineering physics include:

• Computing.
• Biology.
• Medical science.
• Material science.
• Chemistry.
• Physics.
• Mathematics.
• Nuclear science.
• Electrical engineering.
• Electronic engineering.
• Mechanical engineering.
• Thermal engineering and thermodynamics.
• Aerospace engineering and aeronautics.

In engineering physics, a large part of the first years in A-Levels is dedicated to the dynamics of movement, and thermal engineering and thermodynamics. The importance of physics in these areas and in engineering generally is due to physics describing the mechanisms by which the universe and its diverse systems work together.

The dynamics of movement

Movements and their dynamics are one of the main aspects of engineering physics. The study of movement is important because of its wide range of applications in areas such as robotics, space trajectories, particle physics, and any object in motion.

The dynamics of movement uses a simplification of the objects moving and their masses to model them. The model allows us to study how the forces acting on an object affect its movements. Here are some examples of the problems that can be solved by applying the dynamics of movement:

Thermal engineering and thermodynamics

Thermal engineering and thermodynamics study devices that use heat to produce work or use work to modify the temperature of an object or place. Thermal engineering and thermodynamics have a wide range of applications, ranging from engines to energy production and including even biological and chemical processes where energy is involved.

Rotational dynamics

Rotational dynamics is the area of movement dynamics that studies objects moving in a circular or semi-circular path. Rotational dynamics as an area of study includes:

• Angular displacement, including velocity, acceleration, and angular acceleration.
• The analysis of the energy (kinetic and potential), the work, and the mechanical power of an object in rotational movement.
• The analogy between straight-line motion and circular motion.
• Torque and the moment of inertia.

Figure 1. The flying chairs on a carousel are a classic example of rotational dynamics. Source: Tetsumo, Flickr (CC BY 2.0).

Thermodynamics and engines

Thermodynamics is the branch of physics that studies the exchanges of energy in a system. Energy is exchanged as heat or work, causing changes in the system’s temperature. Energy and work changes can cause compression and expansion movements in some gas systems.

Thermal engines

Engines are systems that use energy to produce work or vice versa. A thermal engine uses or produces heat. Engines can also produce work to modify an object’s energy. See the following examples of engines using energy or modifying an object’s energy:

Engines are modelled by thermodynamics, using the work and energy produced and/or absorbed by them.

The relationship between thermodynamics and engines

Engines, such as those found in cars, power plants, or freezers, are modelled as a system that uses or extracts energy in the form of heat. The modelling of an engine, in which thermodynamics is used, ignores many parts of the system to simplify its study. It focuses on how much energy is consumed to produce a certain amount of work.

Thermodynamic modelling is useful in a range of areas, such as those listed below:

Figure 2. Power plants are an example of engines that can be modelled by thermodynamics. Source: Public domain.

The laws of thermodynamics

The study of thermodynamics has been supported by theoretical models that simplify the real objects’ exchange of energy and work. In that way, important results have been achieved that are better known as the ‘laws of thermodynamics’. These laws, which describe the relationship between work, heat, and temperature, are universally applied to every object that exists.

There are four laws of thermodynamics:

1. The zeroth law: the law of thermal equilibrium.
2. The first law: the law that describes the internal energy of a substance.
3. The second law: the entropy law of irreversibility.
4. The third law: the law of the constant value of entropy in a system at absolute zero.