Engineering Physics — A-Level Physics Revision

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What is Engineering Physics?

This optional topic applies physics principles to engineering problems, focusing on two main areas: rotational dynamics and thermodynamics. Rotational dynamics extends the concepts of linear motion to objects that are rotating, introducing moment of inertia, torque, and angular momentum. The thermodynamics section delves into the first law of thermodynamics, explores the properties of heat engines, and analyses thermodynamic cycles using p-V diagrams.

Board notes: Engineering Physics is an optional topic in the AQA specification. It provides a more in-depth study of mechanics and thermodynamics, building on the core concepts of the course. It is particularly suitable for students considering an engineering degree.

Worked example

Common mistakes

• 1Confusing torque with force, or moment of inertia with mass. Torque is the rotational equivalent of force (τ = Iα), and moment of inertia is the rotational equivalent of mass, representing an object's resistance to angular acceleration.
• 2Misinterpreting p-V diagrams. The area enclosed by the cycle on a pressure-volume diagram represents the net work done *by* the engine per cycle. The direction of the cycle (clockwise or anticlockwise) indicates whether it is a heat engine or a refrigerator.
• 3Forgetting that the first law of thermodynamics (ΔU = Q - W) is a statement of energy conservation. A common error is to get the signs wrong for heat (Q) added to the system and work (W) done by the system.

Engineering Physics exam questions

Exam-style questions for Engineering Physics with mark-scheme style solutions and timing practice. Aligned to AQA, Edexcel and OCR specifications.

Frequently asked questions

• What is moment of inertia?

  Moment of inertia is a measure of an object's resistance to being spun. It depends not only on the mass of the object but also on how that mass is distributed relative to the axis of rotation.

• What is the first law of thermodynamics?

  The first law of thermodynamics states that the change in the internal energy (ΔU) of a system is equal to the heat (Q) added to the system minus the work (W) done by the system. It is a restatement of the principle of conservation of energy for thermal systems.