question about a person and a bus while driving.

mick thompson

AKA: Ross Canpolat! SM!
Nov 3, 2005
Dublin, Ireland

ok normally i'd ask something like this on answers or something but i figured nobody there will actually bother to read the question because its so darn long and someone will just post a retarded answer and then my question will never get answered.

anywho... after a big booze up last night i was on the bus this morning going to college with a big mauldy head and this just popped into my mind. i dont know if it was because i was still drunk or what but anyway.. maybe someone can answer it. say there is a man in a bus and he is sitting on a seat and the bus is traveling at 80kmph (mph for you yanks) . suddenly the bus driver decides to break (not very fast but pretty sudden) the man slows down with the bus.

technically the man was traveling at 80kmps/mph but at the same time he was traveling at 0mph/kmph because he was not moving in the cabin.

ok same suituation except this time the man is standing at the back of the bus. the man is moving at 80mph because the bus is moving at 80mph and the bus breaks. the moment the bus driver hits the breaks if the man jumped in the air would he move forward at 80mph (and the bus would be technically slower)

because the man is not standing or touching any part of the bus the instant the breaks are applied there would be no force to slow the man down so would the man suddenly hit the bus's windshield? at 80mph?

or maybe he wouldn't... because as well as the fact that he was moving 80mph/kmph he was also not moving in the bus cab which ment he was going at 0mph/kmph.

he shouldn't hit the screen because he didn't move but he should because his body is moving at 80mph.

so what the hell would happen??????

see i'd test the theory but i dont really plan to have my face smashed into the front of a dublin bus.
I used to know the answer to this, but then I got old. You might move forward a little, but you're not going to hurl towards the windshield at 80mph. Which is a shame, because I think we can all agree that would be funny as all hell (not YOU, but somebody else that nobody knows and doesn't have a family or a cat).
I had this on my mind a lot of times as well... haha It's exactly the same question as the fly in the car. Imagine there's a fly in your car, if you suddenly break would it move? I believe it wouldn't, as it's not physically in touch with the car. It's in the the same "environment" as the car, so to speak, but it isn't being affected by his speed, because the air inside isn't moving. Well I just don't know how to explain it nor I know the answer :D
but how do you know that? because in theory you should hit the windshield at your speed (80) minus the speed of the bus when your feet touch the ground again (say 60) so in theory you should hit the windshield at 20mph/kmph?

like...dont ask why but i jumped into a moving bus a few years ago in dublin and fuck me it hurt. i ran at an angle to get into the moving bus and the second my feet hit the bus after my jump i hit the floor or the bus because in the space of time it took for the speed i was running at and when i jumped until i landed the bus had sped up by about 4 more mph. it was fucking hilarious though (just think about it)

so technically at a greater speed it should be more of a dramatic effect. ie: splattering into the windshield at 20mph.../kmph

and SPTZ technically that means that the fly is moving at the speed of the car (eg 80 mph) and atmosphere does not have a force great enough to suddenly reduce your speed so in theory the fly should hit the screen because he is not touching any part of the car thus meaning nothing is there to slow him down when the car breaks. but then how did he get to that speed (80) in the 1st place if he just flew in and never landed anywhere....or did he...fucking fly!

i think im going to have to call up mythbusters or something...this is recking my head
Seriously, this has always driven me crazy as well! Another way to look at it is to imagine being on a flatbed train car and jumping up; would the train continue to move under you and you would remain staionary in place (so when you landed you'd be like 4 feet behind where you were before), and in turn, if you were to jump up and the train slammed on the brakes (and it's "brakes" btw, not "breaks" ;)), I guess you would fly forward - to me, it's easier when one thinks of it like being on a moving platform, so it makes sense to me!
Hm.. yeah, but you probably would only fly forward just because the train stopped, not because of physics pushing you forward... I don't know... this is mind fucking.

yeah we need jbroll haha
if you jump in the air while its moving, you are technically moving with the vehicle so you don't land 4' behind. If you jump and the brakes are slammed at the point you are in the air, you will fly forward

yeah, I'm sticking with that
if you jump in the air while its moving, you are technically moving with the vehicle so you don't land 4' behind. If you jump and the brakes are slammed at the point you are in the air, you will fly forward

yeah, I'm sticking with that

But, the only reason you fly forward is because the vehicle stopped, so theoretically you're landing on the same place even if it didn't brake... In terms of distance there's the illusion you're going forward because due to lack of movement from the vehicle... :S
Here's a safer test. Next time you're on an elevator (a lift for you foreigners :p ), jump up in the air right before it goes up or down. I suggest down as it's easier on the knees. What happens? Well if you jump right before it goes down you're jumping on a solid platform, but by the time you reach the top of your jump the floor has gone down. So you hit the floor of the lift longer than anticipated.

Okay, now try it again while the lift is moving. Not as fun a result. Why? Because you're body is in sync with the lift (same goes for the bus experiment), so as long as your jumping time and landing time are in sync with the lift, nothing cool happens and all the other mates in the lift think you're a loony.
But, the only reason you fly forward is because the vehicle stopped, so theoretically you're landing on the same place even if it didn't brake... In terms of distance there's the illusion you're going forward because due to lack of movement from the vehicle... :S

You wont go flying because the bus is slowing down and so are you... if the bus came to a complete stop, like say - hitting a 50 inch thick metal wall, you would definitely go flying forward... because the bus stopped, but you didn't... not really sure how to explain it with numbers... but as long as the busdriver isn't suicidal/homicidal, you're ok to try it...
spioraid that elevator trick wont work because 1: the elevator is not moving at free fall speed or remotely fast enough to see any difference and 2 gravity has come into play.

anywho i asked my dad about it. his theory was yes... you would slam straight into the windshield because the atmosphere within the car (not as in wind but the general space that occupies everything that nothing else occupies) is at a constant velocity of the speed of the car (when compared to the outside air) thats why if you open up a window the fly would immediately get sucked out if he is close enough to the window.

someone who has a car can try it out. get a passenger and give him a small ball. you drive the car as fast as your fucking can and when you say "now" slam on the brakes and at the same moment let your mate throw the ball into the air and watch what happens.

sadly im a college student...thus i have no car :-(
Well I would say that when the bus moves at 80mph you also move at 80mph. But when the bus brakes and you don't have a seat belt and all maybe you will not stop in sync with the bus, especially if you are jumping in the air. So if you hit the windshield the reason would be that you weren't synced with the bus because the bus has brakes and you don't? :p

Like, if you put an apple in a plate, you move the plate to the left quickly and then to the right, chances are the apple will continue to the left and go out of the plate. So it would hit the windshield, metaphorically. And the reason would be that the apple does not have enough grip to follow perfectly the vehicle which in this case is the plate? I am no scientist. :p
but thats because of the weight of the apple and its size and a serious speed of plate moving. i think to see that come into play with a human and a bus it would have to be a dam fast speed. im thinking around 600-700 mph to see that effect on the weight of a human
It's a question of relative speed. If you are standing in the aisle on the bus, which is traveling at 50mph, you are also traveling 50mph, because this speed is considered relative to the movement of the Earth, which is considered a baseline of 0 because of the effects of gravity on objects on the surface.

So, if you jump into the air on the bus just as the bus driver applies the brakes, you will continue traveling 50mph while the bus slows down, which will mean that you will land further toward the front of the bus than you were when you jumped.

It's Newtonian physics. An object in motion will tend to stay in motion, and object at rest will tend to stay at rest unless a force is applied to it.

In the case of braking, the bus has the force of the brakes applying friction, which creates resistance, slows it down, and transfers the energy of its forward motion into heat. The passenger who stays in their seat is held in place by a seat belt, or by holding on, which essentially means that they are attached to the bus---so the brakes apply to them as well. The brakes are taking the kinetic energy of the bus and passenger and transferring it into friction.

When the passenger has jumped into the air, the brakes have no resistive effect because the passenger's mass isn't attached to the bus. So, while the forward energy of the bus is being restricted by the brakes, the forward energy of the passenger isn't being restricted by anything other than what friction the atmosphere provides.

In other words, the passenger hits the windshield, or at least lands further down the aisle.
In a real world situation, the rider will only land a bit further up the aisle because of (a) limits to "hang time", assuming we're not talking about Kobe and (b) limits to how quickly a bus can actually stop.
Let's try it in a vacuum!!!
You would still have the 80mph momentum (same reason you keep traveling through the air when you jump while you're running) and since the bus is slowing down while youre continuing to move, you would fly foward in the bus. But gravity will both bring you back down quickly and slow you down quickly since you no longer have the force being applied to you that got you going 80 in the first place.