GCSE Combined Science (AQA)
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Forces in Transport
- Different road vehicles have different masses, accelerations, and legal top speeds.
- Comparison between a typical four-seater family car and a large lorry.
- Legal top speeds on a British motorway: car ~27 m/s (70 mph), lorry ~22 m/s (60 mph).
- Lorry has a harder time reaching higher speeds due to lower acceleration.
- Car acceleration: ~3 m/s��; Lorry acceleration: ~0.4 m/s��.
- Lorry maintains a smaller speed for safety reasons.
- Mass difference: Car ~1,600 kg; Lorry ~36,000 kg.
- Estimation of forces needed to accelerate vehicles to top speed using Newton's second law (Force = Mass x Acceleration).
- Force for car: ~4,800 Newtons (1,600 kg x 3 m/s��).
- Force for lorry: ~14,400 Newtons (36,000 kg x 0.4 m/s��).
- Lorry requires a more powerful engine due to its mass.
- Ability to estimate sensible values for vehicle speeds, forces, and calculate them from estimated masses and accelerations is important.
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