Do you get a little nervous before a flight?
If you do, you're not alone.
Between 33 and 40% of people feel some form of
anxiety when they board a plane.
While a giant metal object flying through the air,
stuffed with people and cargo sure sounds precarious,
planes are actually pretty steady.
Not convinced? Let's do an experiment
here. We have a Boeing
777. It's a full flight,
and we're going to make all 500 passengers jump at
once.
How much force would that exert?
What is natural frequency,
and why are sandbags used on a plane?
This is what if, and here's what would happen if
all the passengers on a plane jumped at once.
You are one of 500 passengers on our Boeing
777. It happens to be the flight captain's birthday and
the flight attendants want to pull a little prank.
They whisper the plan to everyone as they pass out
complimentary snacks.
You are a little unsure of this prank,
but hey, everyone else looks unfazed.
What's the worst that could go wrong?
Balanced weight is extremely important for the safety of an
airplane.
An improperly loaded plane can be dangerous.
It's not just too much weight that you have to
worry about,
but also too little. When planes don't have enough passengers
and cargo,
people have to be moved around the cabin to properly
distribute weight.
Sometimes a flight crew will even have to add sandbags
weighing 23 kilograms each.
So what happens when a bunch of weight is displaced
for just a second?
Well, let's get back to our flight and see.
The airplane has reached altitude and the seat belt light
turns off.
All the passengers, including you,
rise from their seats. The tallest people make their way
to the aisle,
where there's a little more headroom.
You place your hands on the headrest of the seat
in front of you to stabilize yourself.
The flight attendant gives the signal and everyone jumps.
As people's bodies leave the floor of the cabin,
the plane loses
37,500kg of weight. Because the plane is lighter,
it will rise in altitude as passengers leave the floor.
Together, you and the other passengers exert the force of
about 10 elephants or
800 people. This sudden push of weight changes the plane's
trajectory and the captain loses control as the plane nose
dives to your untimely death.
Wait, that doesn't sound right.
Rewind.
This sudden push of weight changes the plane's trajectory and
nothing really happens. Because the plane is travelling at around
870 kilometres per hour, this collective jump only created a
minor change in trajectory.
The captain can easily adjust,
though he may be a little annoyed at all his
pesky passengers
now. This is assuming that all 500 passengers have an
average weight of 75 kilograms,
for a total weight of
37,500 kilograms. It would be a different story if it
was a flight full of 500 sumo wrestlers who can
weigh up to 200 kilograms each.
It would also be a much more dangerous stunt to
pull during takeoff or landing.
The plane has a much lower velocity during those moments,
which means that the shifting of weight could have a
more drastic effect on the trajectory
and the captain might not be able to correct in
time.
Now, if everyone decided to continue to jump In Sync
and at a quick enough pace,
you could create an unstable condition called flutter.
This vibration originates from the airplane causing unsteady aerodynamics which
affects the natural frequency of the plane.
Natural frequency is the set of frequencies that an object
vibrates at when hit.
If the vibrations from passengers continuously jumping caused flutter,
then the structure of the airplane could fail and you
would drop out of the air.
But the coordination of this would be near impossible,
so it's not something you really have to worry about.
Despite many people's anxieties, flying is actually very safe.
Airplanes are safer than both trains and cars,
although if everyone had a personal airplane or a flying
car,
then traveling by air might not be as safe.
But that's a story for another
What if?