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Figure 15 is a speed limit sign from a European motorway - Edexcel - GCSE Physics - Question 9 - 2022 - Paper 1
Question 9
Figure 15 is a speed limit sign from a European motorway. The speeds shown are in km/h (kilometres per hour). (i) The sign tells drivers to drive at a slower speed ... show full transcript
Worked Solution & Example Answer:Figure 15 is a speed limit sign from a European motorway - Edexcel - GCSE Physics - Question 9 - 2022 - Paper 1
Step 1
Explain why it is safer for drivers to drive at a slower speed in wet weather.
Answer
Driving at a slower speed in wet weather is safer for several reasons:
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Reduced Friction: Wet roads decrease the friction between the tires and the road surface, meaning that vehicles may not grip the road as well. This can lead to a higher risk of skidding, which is more likely at higher speeds.
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Increased Stopping Distance: Wet conditions increase the distance needed to bring a vehicle to a stop. By driving slower, drivers have more time to react and stop safely, reducing the likelihood of collisions.
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Visibility Issues: Rain can reduce visibility; therefore, a slower speed allows drivers more time to react to unexpected situations caused by poor visibility.
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Loss of Control: Slower speeds can help in maintaining control of the vehicle, especially when turning or navigating through puddles that may cause hydroplaning.
Step 2
Show that a speed of 31 m/s is less than a speed of 130 km/h.
Answer
To compare the two speeds, we need to convert them to the same unit. We can convert 130 km/h to meters per second (m/s).
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Conversion Factor: We know that 1 km = 1000 m and 1 hour = 3600 seconds. Thus,
rac{130 ext{ km}}{1 ext{ h}} = 130 imes rac{1000 ext{ m}}{1 ext{ km}} imes rac{1 ext{ h}}{3600 ext{ s}}
Evaluating this gives:
= 130 imes 0.2777 ext{ m/s} \ \ = 36.1 ext{ m/s}$$ -
Comparison: Now we have:
- 31 m/s
- 36.1 m/s (which is 130 km/h)
Since 31 m/s < 36.1 m/s, we conclude that 31 m/s is indeed less than 130 km/h.