James McEwan, of Invercargill, asks :-
What is the people-carrying vehicle which has the most kinetic energy?
Craig Rodger, a physicist at Otago University, responded.
Kinetic energy is the energy associated with a moving body and depends on only two quantities. It is proportional to the mass (m) of the object and the square of the body's speed (velocity v) (KE = half of the mass multiplied by the speed multiplied by the speed again). So to get a large amount of kinetic energy we normally concentrate on fast moving vehicles rather than really heavy vehicles.
The fastest moving human beings that I know of were the three Apollo 10 astronauts during their return from a mission to the moon's orbit. As the 5500 kg Apollo 10 command module re-entered the Earth's atmosphere the capsule's velocity peaked at 11.1 kilometres per second. At this time their kinetic energy will have been 0.68 million million joules!
Getting into space is an exercise in brute force, requiring huge rockets burning massive amounts of fuel, and so we should also consider the launch into space. If you decided that the "people carrying vehicle" was the crew's little command module plus the huge Saturn V rocket that took them away from Earth we have a different calculation. The kinetic energy peaked at about 11.1 million million joules somewhere around 217 km altitude when the rocket was travelling at 23,464 km per hour and had a mass of 261,505 kg. How did the kinetic energy get so large? The Saturn V rocket started off on the ground with a mass of about 3 million kilograms, had burnt more than 2.5 million kilograms of fuel by the time it reached that altitude and speed, and was travelling in space where there is no air friction.
To put this amount of energy into perspective, if it was converted completely into electrical energy it would supply the electrical power needed to run the Dunedin Electricity network for one day.