Engineering Physics | AQA A-Level Physics (7408)
Engineering Physics
- 290 questions
- 12 subtopics
- Paper 3 Section B: one option of five
- Paper 3
Engineering physics is one of the five optional topics, sat on Paper 3.
It has two halves: rotational dynamics, which mirrors linear mechanics with moment of inertia in place of mass, and thermodynamics, which covers the gas processes and the engines built on them.
Sample questions from Engineering Physics
Answer each one closed book first, then open the answer.
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Concept of moment of inertia
Explain why the moment of inertia of an extended object is calculated as a summation rather than a single product.
Show the answer
An extended object consists of many mass elements at different distances from the axis, so each element's contribution (mr²) must be summed to find the total moment of inertia. -
Rotational kinetic energy
Describe how a flywheel reduces variations in rotational speed during operation.
Show the answer
The flywheel stores energy during periods of excess power input and releases it during periods of high demand, thereby reducing variations in rotational speed. -
Torque and angular acceleration
What is the linear motion equivalent of the equation T = Iα?
Show the answer
F = ma (Newton's second law), where force replaces torque, mass replaces moment of inertia, and linear acceleration replaces angular acceleration. -
Angular momentum
Calculate the angular momentum when moment of inertia = 43.9 kg m², angular velocity = 18.5 rad s⁻¹.
Show the answer
Angular momentum = 43.9 × 18.5 = 812 kg m² s⁻¹. -
First law of thermodynamics
Explain why W is positive when a gas expands against external pressure.
Show the answer
The gas does work on its surroundings, transferring energy out of the system, which by convention is defined as positive work done by the system. -
Non-flow processes
For a constant volume process, how does the heat supplied relate to the internal energy?
Show the answer
Q = ΔU; all heat supplied increases the internal energy of the gas. -
Engine cycles
State the formula for input power of an engine in terms of fuel properties.
Show the answer
Input power equals the product of calorific value and fuel flow rate: P_input = calorific value × fuel flow rate. -
Second Law and engines
Calculate the maximum theoretical efficiency when temperature of hot reservoir = 850 K, temperature of cold reservoir = 330 K.
Show the answer
Maximum theoretical efficiency = (850 - 330) ÷ 850 = 0.612.
The 12 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Concept of moment of inertia | Moment of inertia as resistance to angular acceleration, and why shape matters as much as mass. | 16 |
| Rotational kinetic energy | The ½Iω² formula, and the flywheel as an energy store. | 14 |
| Rotational motion | Angular displacement, velocity and acceleration, the rotational equations of motion, and the graphs. | 37 |
| Torque and angular acceleration | Torque as the rotational analogue of force, and T = Iα. | 18 |
| Angular momentum | Conservation of angular momentum, angular impulse, and the spinning skater. | 20 |
| Work and power | Work done by a torque, power transmitted by a rotating shaft, and the effect of friction. | 14 |
| First law of thermodynamics | Q = ΔU + W, the sign conventions, and isothermal and adiabatic changes. | 26 |
| Non-flow processes | Isothermal, adiabatic, constant pressure and constant volume changes, and the work done in each. | 33 |
| The p–V diagram | Reading work from the area under a curve, cyclic processes, and the direction of the loop. | 18 |
| Engine cycles | The four-stroke petrol and diesel cycles, indicator diagrams, and input, brake and friction power. | 39 |
| Second Law and engines | Why a heat engine must reject heat, thermal efficiency, and the maximum theoretical efficiency. | 27 |
| Reversed heat engines | Refrigerators and heat pumps, the coefficient of performance, and why it can exceed one. | 28 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
AQA A-Level Physics Active Recall Guide
Every topic, not just this one. 3,682 questions with their answers.