Passengers in Sudden Plane Vertical Drop: Effects

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ellieee
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Homework Statement
exact qn:
when airplane suddenly drops down Vertically, why do people hit the ceiling of the airplane?
is it something about inertia? but I was also thinking about newton's third law. when plane drops down(force is downwards), then I go upwards cuz it's the opposite force?
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nil
 
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ellieee said:
is it something about inertia?
Yes.
ellieee said:
but I was also thinking about Newton's third law. when plane drops down(force is downwards), then I go upwards because it's the opposite force?
Please quote that law, then check whether it fits this circumstance.
 
may I know the explanation?
haruspex said:
Yes
 
haruspex said:
We don't do your homework for you. Please show some reasoning.
What forces act on a passenger?
gravitational force
 
haruspex said:
Before or after the plane drops suddenly?
is it both? I think it's because when you're not moving, gravitational force will still act on you.
 
Delta2 said:
don't we need to know if the plane falls down with acceleration less, equal or greater than g?
but the question didn't state the value of the acceleration of the plane
 
ellieee said:
but the question didn't state the value of the acceleration of the plane
Ok then its up to you to take the cases ##a<g,a=g,a>g##. From what I can understand in the first two cases the passengers won't hit the ceiling...
 
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ellieee said:
but the question didn't state the value of the acceleration of the plane
Usually (maybe even always) if a questions says 'drop' it means under gravity, so the acceleration is the acceleration due to gravity, unless you're given info regarding other forces such air resistance, which you're not in the case.

I can't imagine a situation where a place falls with an acceleration greater than g which doesn't involve Bond like baddies with huge magnets somewhere.
 
rsk said:
acceleration is the acceleration due to gravity
but isn't gravitational force always acting on the plane? shouldn't the value of the acceleration be greater than acceleration due to gravity ?
 
ellieee said:
but isn't gravitational force always acting on the plane?
Yes, but it is not the only force on the plane.
rsk said:
I can't imagine a situation where a place falls with an acceleration greater than g which doesn't involve Bond like baddies with huge magnets somewhere.
I can.
 
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haruspex said:
Yes, but it is not the only force on the plane.

I can.
there's also lift;upward acting force, thrust; the forward acting force; and drag, the wind resistance
 
haruspex said:
Good, but how could the sum of those result in the plane accelerating downward faster than g?
the lift force decreases ?
 
haruspex said:
Could that lead to a downward acceleration faster than g?
hmm why not? if lift force decreases, then resultant force would be downwards no?
 
ellieee said:
hmm why not? if lift force decreases, then resultant force would be downwards no?
Lift force is an upward force.
Decrease in an upward force doesn't change gravity

I think in the question we are to assume that the plane is in free fall.
The passengers tend to be in rest due to inertia
And then you know what happens!
 
Shreya said:
Lift force is an upward force.
Decrease in an upward force doesn't change gravity

I think in the question we are to assume that the plane is in free fall.
The passengers tend to be in rest due to inertia
And then you know what happens!
That does not work. The passengers would also be in free fall.
 
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haruspex said:
That does not work. The passengers would also be in free fall.
Yes, but they will take some time to get to same velocity as the plane is.
 
haruspex said:
Why?
I think I got it wrong.
The plane must be experiencing acceleration greater than g (due to turbulence)
If the air pressure above the wings becomes higher (somehow) than the air pressure below the wing.
The lift could act downward.
 
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Shreya said:
I think I got it wrong.
The plane must be experiencing acceleration greater than g (due to turbulence)
If the air pressure above the wings becomes higher (somehow) than the air pressure below the wing.
The lift could act downward.
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