Understanding how to approach exam questions helps to boost exam performance. Questions will include multiple choice, descriptions and explanations, using mathematical skills, and extended writing.

Part of

You will complete 21 required practical activities if you are studying GCSE Combined Science: Trilogy. You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.

There will be a number of different types of practical based questions. Some will be on the set required practicals, some will cover the working scientifically terms and some will be on other science practicals which you might have done in class. Use all the information given in the question particularly any diagrams to help you understand what the question is about.

*This page contains AQA material which is reproduced by permission of AQA.*

- Question
A student investigated the efficiency of a motor using the equipment below:

He used the motor to lift a weight of 2.5 N a height of 2.0 m.

He measured the speed at which the weight was lifted and calculated the efficiency of the energy transfer.

He repeated the experiment to gain two sets of data.

**a)**Give one variable that the student controlled in his investigation.**[1 mark]****b)**Give two reasons for taking repeat readings in an investigation.**[2 marks]****a)**Weight (lifted)*or*height (lifted). [1]Control variables are those kept the same to ensure a fair test. The second sentence in the question highlights two things he kept the same.

**b)**Any**two**from:- calculate a mean
- spot anomalies
- reduce the effect of random errors

[2]

Two of the three points should be used from the list above to secure the total two marks.

- Question
A student investigated how much energy from the Sun was incident on the Earth's surface at her location.

She put an insulated pan of water in direct sunlight and measured the time it took for the temperature of the water to increase by 0.6°C.

The apparatus she used is shown in the diagram.

**a)**Choose the most appropriate resolution for the thermometer used by the student.**[1 mark]**Tick

**one**box.A 0.1°C B 0.5°C C 1.0°C **b)**The energy transferred to the water was 1,050 J. The time taken for the water temperature to increase by 0.6°C was five minutes. The specific heat capacity of water is 4,200 J/kg °C.Write down the equation which links energy transferred, power and time.

**[1 mark]****c)**Calculate the mean power supplied by the Sun to the water in the pan.**[2 marks]****d)**Calculate the mass of water the student used in her investigation.Use the correct equation from the Physics Equation Sheet.

**[3 marks]****a)**A 0.1°C ✔ B 0.5°C C 1.0°C Resolutions of 0.5°C or 1.0°C would not allow a temperature of 0.6°C to be measured accurately.

**b)**energy transferred = power × time [1]You must learn this equation for the exam.

**c)**= 1,050 ÷ (5 x 60) [1]

= 1,050 ÷ 300

= 3.5 W [1]

Show all steps of the calculation and include units in the answer.

**d)**Change in thermal energy = mass × specific heat capacity × temperature change [1]Mass = change in thermal energy ÷ (specific heat capacity × temperature change) [1]

= 1,050 ÷ (4,200 × 0.6)

= 1,050 ÷ 2,520

= 0.42 kg [1]

As the question states, the equation can be copied directly from the Physics Equation Sheet. Write the equation out in full, and then show all stages of working out.