Why is it on the bus you jump
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He's talking about relative velocity and frames of motionOriginally posted by limywv:what toking you? -
i tink becos is newton 1st law, constant speed, u are moving with the train , when u jump, it goes up, but no push or pulling force
if the train accelerates, not constant speed, then u will go back?
ok, who can do an illustration? -
Originally posted by ditzy:Coz you're moving with the fcuking bus.
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Ok, i wonder why are we concern about this, no matter how u jump on a bus, u will eventually being instrusted by the captain to sit down, and u will reach ur destination
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i will now give the most logical answer...Originally posted by AMEN567889:Why is it on the bus you jump, u will still land on the exact same spot?
Hint: think of projectile motion
u will still land on the exact same spot because there is someone behind you..so you cant exactly push him away and land on his spot instead
i actually replied
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no. u will b teleported to another dimension where u can ask the beings dere about ur curiousity.
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hahaha. brush up on your physics first lah. you level one skill is not even there. Inertia is not defined that way. Instead, it is "The unwilling of an object to change its state of motion or resists acceleration"Originally posted by Scania N113CRB luver:Wrong ! Inertia has nothing to do here. Only when starting off and slowing down then inertia comes into effect .
Inertia is termed as "The unwillingness of an object to start moving from rest and the unwillingness of an object to stop while moving."
A heavier object will have greater inertia as mass is the measurement of inertia (at least, loosely saying)
As for the fly, in a vacuum, assuming that the fly doesn't explode due to blood pressure or whatever, it will follow the same rules as in a filled gas chamber. There is nothing to do whether that is air, or helium, or any other thing. But there is something to note here, I'm assuming that the object is denser than the fluid medium. (iirc, it makes a difference) -
Cheem ...
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COOL!Originally posted by Vigelic:Food for thought: If the Earth stopped spinning all of a sudden, what would you do?
Note: The Earth spins at a speed of 1,670 km/h from west to east. (Speed at equator) - which means that your keyboard is moving at 1,670km/h as well!
(speed of earth's orbit around the sun and the speed of the solar system's movement relative to the milky way and the universe not factored into this equation)
P.S. if the Earth stopped spinning right now, everything would fly at a speed of 1,670 km/h towards the east initially. Just imagine Earth as the bus doing an E Brake and everything else as the dumb idiot who tried jumping during an E brake.
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Because you are moving relative to the bus. You may appear to be in a projectile motion when you jump to a random auntie digging her nose on a pathway, but you may also appear to be jumping on the exact spot to the furious bus driver. Since the bus is your reference frame, and you are jumping at the same spot relative to the bus, you will stay in the exact spot when you jump.
Motion is relative
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inertia?
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sigh let's talk about the fly first
we assume a fly in vacuum somehow managing to hover(which alone defies physics) in midair when the train starts moving. In this case, the fly is no different from a fly that's outside the train. It's relative velocity to the train will increase as the train accelerates away. Long story short, the fly will eventually hit the back of the train.
If there is air however, and we assume an airtight train, ie, closed system, the same fly will never hit the back of the train. Because the fly is in contact with the train via the medium of air, it will move along with the train.
The question of the boy jumping up on a moving train is even simpler, and has nothing to do with projectile motion. To an observer standing beside the tracks, the boy and the train are travelling at the exact same horizontal velocity before the boy jumps.
When the boy jumps, all force exerted by him on himself (actually, to the train first via newton's third law) is assumably purely on the vertical axis. Since there is no net force on the horizontal axis, his velocity remains constant. Since velocity of boy in horizontal direction matches the train, he will move the exact same distance in the direction of travel the train takes.
Obviously if the train changes it's horizontal acceleration while the boy is in midair, the boy will land on a different spot.
As for the helicopter hovering, hovering for half a day in midair will not put it around the world. If that were true, we could travel to Europe by jumping on the spot for a couple of hours. Someone mentioned on the first page this phenomena was not inertia. In actuality, this is exactly what it is. -
Originally posted by deathbait:
Imagine the train coming to a sudden stop while he is still in the air... ouch.
Obviously if the train changes it's horizontal acceleration while the boy is in midair, the boy will land on a different spot. -
how sudden? 80 to 0 kmh in 0.001 second?Originally posted by Deadly:Imagine the train coming to a sudden stop while he is still in the air... ouch. -
well...
if the bus slows down from 80km/h to 40km/h in 1 second via the E brake, and the boy is in the air for that 1 second, it would still be painful.
80km/h = 1330m/min = ~22 meters per second
And that's just displacement.
Even if the boy was standing at the back end of the bus when he jumped, and the 22 meter displacement didn't put him against the front of the bus, he's still travelling at a net 40km/h forwards when his feet touch the floor of the bus.
Even if we assume he has the braking power to reduce that by half, 20km/h smash into a solid object can still be a painful experience. -
nice explanationOriginally posted by Vigelic:never mind. i don't know why i bothered.
off topic: putting FI old sig is a trend now ah? -
he probably wouldn't mind if the solid object was a girl insteadOriginally posted by deathbait:well...
if the bus slows down from 80km/h to 40km/h in 1 second via the E brake, and the boy is in the air for that 1 second, it would still be painful.
80km/h = 1330m/min = ~22 meters per second
And that's just displacement.
Even if the boy was standing at the back end of the bus when he jumped, and the 22 meter displacement didn't put him against the front of the bus, he's still travelling at a net 40km/h forwards when his feet touch the floor of the bus.
Even if we assume he has the braking power to reduce that by half, 20km/h smash into a solid object can still be a painful experience. -
lol. but he hit into a girl at a speed so fast the only thing he will feel is PAIN. and after that the girl (and him) might have a broken bone or something =/
i don't think will have happy ending.