AQA A-level 2025/2026 PHYSICS 7408/3BC Paper 3 Section B Question Paper + Mark Scheme + Insert Answer all questions in this section.
0 1 A heavy turntable is mounted on a fixed base. The turntable can rotate freely on a
low-friction bearing.
0 1 . 1 Figure 1 shows a propeller unit fixed to the centre of the turntable.
The propeller unit consists of a motor-driven propeller and a battery.
The propeller and the turntable have a common axis of rotation.
Figure 1
At first, the turntable and the propeller are at rest.
The propeller motor is switched on and the propeller quickly reaches a high final
angular speed.
The propeller rotates clockwise when viewed from above.
Compare, with reference to angular momentum, the motions of the turntable and the
propeller.
[3 marks]
Question 1 continues on the next page
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0 1 box . 2 Figure 2 shows an arrangement used to determine the moment of inertia of the
turntable.
Figure 2
A small steel mass is held by an electromagnet above the top surface of the turntable.
The diameter of the turntable is about half a metre.
The turntable rotates freely at an initial angular speed ω1.
The switch is opened so that the mass falls and sticks to the surface of the turntable.
This changes the angular speed of the turntable to ω2.
The steel mass can be considered to be a point mass.
Describe how to determine the moment of inertia of the turntable using observations
of ω1 and ω2.
In your answer you should:
• suggest how ω1 and ω2 are measured
• state any other measurements needed and name the equipment used to make
them
• explain how the moment of inertia of the turntable is determined from the
measurements.