Scary that so many do not even know simple high school physics. Doubling velocity (speed) does not double energy. It quadruples energy. Everyone here should know that. Otherwise scammers and politicians make money and get elected because the public is uneducated and naive. These fundamental facts are taught to everyone in high school to make dishonesty and scams difficult.
Energy of one car at 100 km/hr is equal to the energy of two cars at 70.7 km/hr. Basic physics. Obviously. Posting again is what everyone should have known when the OP first asked his question:
Energy = one half mass times velocity squared.
Irishman - if you know that is wrong, then you have posted numbers and equations that says so. Subjective claim or denial suggests outright lying or lack of basic high school education. Honest answers always include the numbers. So, where are your numbers? The always required numbers when you insist someone is wrong.
Explain how two cars at 50 km/hr is energy equal to one car at 100 km/hr? Explain means posting the numbers.
Energy in a 100 Km/hr car is one half times its mass times 100 squared. Energy in each 50 km/hr car is one half times the same mass times 50 squared. Please show everyone how that energy is equal. You claimed it is so – but only subjectively. Prove it. A point I make often because scammers and politicians can only exists when numbers are replaced by subjective denials (also called hearsay or junk science).
Why must every adult know this? Because a car doing 100 km/hr (or 70 mph) requires twice as much braking to stop. As compared to a car only doing 70 .7 km/hr (50 mph). But then every high school graduate is required to know this. Otherwise jobs must go overseas to those who did learn what is critically important – the numbers. Show me your numbers or withdrawal subjective (empty) denials.