2. (a) A train is powered by a diesel engine - Edexcel - GCSE Physics - Question 2 - 2013 - Paper 1
Question 2
2. (a) A train is powered by a diesel engine.
The diesel engine is used to turn a generator.
The generator provides electricity for electric motors which drive the w... show full transcript
Worked Solution & Example Answer:2. (a) A train is powered by a diesel engine - Edexcel - GCSE Physics - Question 2 - 2013 - Paper 1
Step 1
(i) Draw one straight line from each train part to its useful energy transfer.
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Answer
Lines should connect each train part to its corresponding useful energy transfer:
Diesel engine → Chemical to Electrical
Generator → Electrical to Kinetic
Motor → Kinetic to Electrical
Additional option: Motor → Kinetic to Chemical.
Step 2
(i) Calculate the amount of energy wasted in one second in the generator.
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Answer
The amount of energy wasted can be calculated as follows:
Energy Wasted = Energy Supplied - Useful Energy
Substituting the values:
Energy Wasted = 1400 kJ - 1300 kJ = 100 kJ.
Step 3
(ii) Calculate the efficiency of the generator.
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Answer
To calculate the efficiency of the generator, we use the formula:
Efficiency = (Useful Energy / Energy Supplied) × 100%
Substituting the values:
Efficiency = (1300 kJ / 1400 kJ) × 100 = 93%.
Step 4
(c) Suggest why the motors are painted black.
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The motors are painted black because black is a good thermal radiator, which helps to prevent overheating by allowing the motors to dissipate heat more effectively.
