Answer 1:
If the elevator is going at a constant speed, then
the person's weight would not be any different
than if it were standing still, no matter ifthe
elevator was going straight up or
diagonally. To feel a difference in the
person's weight, the elevator would have to be
accelerating. So, if a person was in an elevator
that was ACCELERATING upward, s/he would feel
heavier during this time. Suppose two elevators
were accelerating at the same rate, that is,
getting faster and faster each second by the same
amount, but one was going directly vertically, 90
degrees to the flat ground, and the other was
going up at an angle that was less than 90, say at
an angle of 30 degrees up from the flat ground,
and say that both had accelerations of
2meters/second^2.The one in the vertical elevator
would feel about 20% heavier than if she were not
accelerating, and the one in the diagonal elevator
would feel about 10% heavier than normal. I knew
this because the vertical component contributes an
amount in proportion to the sine of the angle, in
this case30 degrees. The sine of 30 is 0.5. I
don't know if you've done this in math yet, so ask
your teacher to explain it. The reason for this
is that you add the mass x acceleration to the
weight of the person, which is mass x "g". g is
the acceleration of free falling objects close to
the surface of the earth, and it is about
10meters/second^2. If the elevator is going at
an angle, then only the vertical component of the
acceleration adds to the increase in
weight. But, there's more: you asked about the
total force on the person. Well, in the diagonally
accelerating elevator there is also a HORIZONTAL
component of force on the person, so he or she
would feel pushed back toward the wall, like you
feel pushed backwards in your seat when the car
you'reriding in accelerates forward. And that
component is proportional tosomething called the
cosine of the angle, in this case 30 degrees. The
cosine of 30 is about .86, so for a total
acceleration of 2meters/second^2, this is about
1.7 times the mass of the person, or about17
percent heavier. So: for the vertical elevator,
accelerating upward at 2 meters/second^2,there is
no sideways force, and the person feels about 20%
heavier. For the diagonal elevator, the person
feels about 10% heavier in the vertical direction,
and there is a sideways force on her that is about
17% of her weight. BUT  you have to remember
that this is ONLY for accelerating elevators.If
they're going at a constant velocity then there is
NO extra force.

Answer 2:
From classical physics, Force = mass x
acceleration.So, for a person at rest, their
weight is simply their mass times the acceleration
due to gravity. Now, for both cases you
described, their weight would still be exactly the
same since the elevator in both cases is traveling
at constant speed. If there is no acceleration,
then there cannot be any "extra" force. Think
about when you get on an elevator to go up. When
the elevator first starts, you'll feel "heavy"
because the elevator is accelerating. But if you
were going up a long ways and the elevator speed
became constant, you no longer feel the extra
force, and if it's a smooth ride, you won't be
able to tell if you're moving or stationary.
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