Quietm02 t1_je8rn59 wrote on March 30, 2023 at 6:20 AM

Reply to comment by bureau44 in eli5 What would happen if I had a big enough airplane to throw a ball around then the airplane turns while the ball is in mid air? by the_lost_cheeto

Imma say no.

Helicopter works by pushing air down. That air hits the floor of the plane, giving the same "weight" as the helicopter just sitting there anyway.

A real interesting question is what happens if I have a big train going half the speed of light. Then stick another train on top going half the speed of light. Does the second train go at the speed of light?

bureau44 t1_je9a0l2 wrote on March 30, 2023 at 10:40 AM

Sure it won't.

As with speed of light the answer is also no even if you put a third train on top of the second. But I fear I am not able to eli5 this.

Quietm02 t1_je9e5e7 wrote on March 30, 2023 at 11:27 AM

You're right it won't. The short answer is that adding velocity together is an approximation that only works for low speeds. It doesn't work when you get near the speed of light.

This link explains better than I can https://galileo.phys.virginia.edu/classes/252/adding_vels.html