I’m so glad you asked !
1). If the bathtub is big enough to accommodate the length, width, and draft
of the ship, and the tub is full of water, then the ship floats in the tub.
(Strange as it may seem, the same can be said of the planet Saturn.)
2). Momentum is conserved. ===> The total momentum of (car + bug)
is the same before and after the collision. ===> The impulse imparted
to the car is equal to the impulse imparted to the bug. ===> F₁·t = F₂·t .
===> For every action, there is an equal and opposite reaction.
===> The force exerted on the bug is equal to the force exerted on the car.
===> The bug sustains more damage than the car does.
3). This simple-sounding question is actually a very complicated question.
… You said “an electron”. Do you mean the same electron ? Or do you mean
the electric current ?
… The ‘drift velocity’ of the same electron is only millimeters per hour.
… If you’re plugged into a common AC wall socket, then a single electron is
pulled this way, then that way, 60 times a second, and never gets anywhere.
… Electric current flows by means of one electron bumping the next one,
which bumps the next one, which bumps the next one, which bumps the
next one, and so on all along the wire. So the EFFECT shows up at the
other end of the wire much faster than any single electron gets there.
… That speed depends on the thickness and composition of the wire,
the thickness and composition of the insulation around the wire, the
distance between the two wires in the power cord, and some other things.
It can range anywhere from 45% to 99% of the speed of light.
— If your power cord is 5 feet long and the propagation velocity is 0.99c,
then the answer to your question is 0.000 000 005 13 second.
— If your power cord is 10 feet long and the propagation velocity is 0.45c,
then the answer to your question is 0.000 000 022 6 second.
The actual situation is somewhere in that range.
4). When you toss a ball or a stone straight up, it goes up for a while
as it slows down, then turns around, then falls for a while as it speeds up.
It’s fairly easy to prove that it returns to your hand with the same speed
as you tossed it.
So if you toss two stones, with the same speed, from the same height,
one up and one down, then the one that went up and came back has the
same speed as it passes your hand going down.
They both hit the ground with the same speed.
But there IS one difference: The one you tossed UP hits the ground LATER !