A-LevelPhysicsThermodynamicsMay/June 2020Paper 5 Q215 Marks
A student investigates how the viscous force in a liquid varies with temperature. The student releases a ball from the surface of the liquid in a container. The ball falls as shown in Fig. 2.1. [Figure 2.1] The student determines the speed of the ball between P and Q and measures the thermodynamic temperature T of the liquid. Viscosity is a term used to describe the viscous forces acting in a liquid. Viscosity has the unit pascal second (Pa s). The viscosity η of the liquid is calculated from the speed of the ball. The experiment is repeated for the same liquid at different temperatures. It is suggested that η and T are related by the equation η = He^(E/(kT)) where E and H are constants and k is the Boltzmann constant.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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