Cyclists Now Outnumber Motorists in City of London

Re:Cyclists Now Outnumber Motorists in City of London by loeg on Monday March 20, 2023 @11:44AM (#35233286)

Energy is proportionate to the square of velocity. So it's:

Walking: 5 km/h * 70kg => 875 (although this is a very slow estimate for a walker) (please ignore the non-canonical units)

e-bike: 20 km/h * 90 kg => 18,000 (I think your estimate for ebike mass might be on the low side at 20kg, but whatever)

car: 50 km/h * 2000kg => 2,500,000 (and that's a fairly low speed for cars! Drunk drivers often drive faster than is wise.)

Everything else is a rounding error compared to the energy of a car.

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Re:Cyclists Now Outnumber Motorists in City of London by codethief on Monday March 20, 2023 @12:22PM (#35233928)

Initial kinetic energy is not the right physical quantity to look at. Most of that kinetic energy will remain in the car/bike/…, i.e. it doesn't tell you much about how much energy will get transferred to the victim – it merely gives you a bound from above.

More details: https://news.ycombinator.com/item?id=35233887

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Re:Cyclists Now Outnumber Motorists in City of London by uoaei on Monday March 20, 2023 @11:55AM (#35233466)

Realistic estimates:

Walking: 6kph, 70kg => 100J (0.02% of car)

Analog bike: 18kph, 80kg => 2kJ (0.36% of car)

E-bike: 25kph, 100kg => 4.6kJ (0.82% of car)

Car: 50kph, 2000kg => 560kJ (100% of car)

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Re:Cyclists Now Outnumber Motorists in City of London by loeg on Monday March 20, 2023 @12:05PM (#35233639)

Thanks. Just for the sake of fleshing out the speeding angle:

Car, 64 kph => 164% of car at 50 kph

Car, 110 kph => 480% of car at 50 kph

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Re:Cyclists Now Outnumber Motorists in City of London by Someone on Monday March 20, 2023 @01:40PM (#35235435)

* * *

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