The discussion centers on the physics of passengers experiencing a sudden vertical drop in a plane, focusing on the forces at play, particularly gravitational force and lift. Participants explore Newton's third law and the conditions under which passengers might experience different accelerations relative to the plane's descent. It is established that if a plane drops with an acceleration greater than gravitational acceleration (g), passengers will experience a sensation of weightlessness, as they are in free fall. The conversation emphasizes the importance of understanding the balance between lift and gravitational forces during such an event.
PREREQUISITESAerospace engineers, physics students, aviation safety professionals, and anyone interested in the dynamics of flight and passenger experiences during turbulence.
Yes.ellieee said:is it something about inertia?
Please quote that law, then check whether it fits this circumstance.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?
haruspex said:Yes
We don't do your homework for you. Please show some reasoning.ellieee said:may I know the explanation?
gravitational forceharuspex said:We don't do your homework for you. Please show some reasoning.
What forces act on a passenger?
Before or after the plane drops suddenly?ellieee said:gravitational force
is it both? I think it's because when you're not moving, gravitational force will still act on you.haruspex said:Before or after the plane drops suddenly?
but the question didn't state the value of the acceleration of the planeDelta2 said:don't we need to know if the plane falls down with acceleration less, equal or greater than g?
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...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.ellieee said:but the question didn't state the value of the acceleration of the plane
but isn't gravitational force always acting on the plane? shouldn't the value of the acceleration be greater than acceleration due to gravity ?rsk said:acceleration is the acceleration due to gravity
Yes, but it is not the only force on the plane.ellieee said:but isn't gravitational force always acting on the plane?
I can.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.
there's also lift;upward acting force, thrust; the forward acting force; and drag, the wind resistanceharuspex said:Yes, but it is not the only force on the plane.
I can.
Good, but how could the sum of those result in the plane accelerating downward faster than g?ellieee said:there's also lift;upward acting force, thrust; the forward acting force; and drag, the wind resistance
the lift force decreases ?haruspex said:Good, but how could the sum of those result in the plane accelerating downward faster than g?
Could that lead to a downward acceleration faster than g?ellieee said:the lift force decreases ?
hmm why not? if lift force decreases, then resultant force would be downwards no?haruspex said:Could that lead to a downward acceleration faster than g?
The vertical forces on a plane are, generally, gravity and lift, roughly in balance. With zero lift, what would the acceleration be?ellieee said:hmm why not? if lift force decreases, then resultant force would be downwards no?
Lift force is an upward force.ellieee said:hmm why not? if lift force decreases, then resultant force would be downwards no?
That does not work. The passengers would also be in free fall.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!
Yes, but they will take some time to get to same velocity as the plane is.haruspex said:That does not work. The passengers would also be in free fall.
Why?Shreya said:Yes, but they will take some time to get to same velocity as the plane is.
I think I got it wrong.haruspex said:Why?
Let's give @ellieee a chance to contribute.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.