An easy physics question?
Discussion
esselte said:
If I stood at the back door of a train travelling at 70mph through a station and threw a ball directly behind the train at 70mph,what would an observer on the platform see?Would he see the ball just drop to the ground or would something else happen?
Barring some minute relativistic correction, or aerodynamic interference from the air dragged along by the train etc. etc. he would see it drop.
s2art said:
If I stood at the back door of a train travelling at 70mph through a station and threw a ball directly behind the train at 70mph,what would an observer on the platform see?Would he see the ball just drop to the ground or would something else happen?
Barring some minute relativistic correction, or aerodynamic interference from the air dragged along by the train etc. etc. he would see it drop.
What about air resistance on the ball?
The ball in reality would get buffeted around by the turbulence at the back of the train, but as said, ignoring that , if the train is traveling at 70mph and the ball is thrown directly opposite at 70mph then its velocity relative to the earth is 0.
If it was something heavy like a canonball it wouldnt get buffeted so much and literaly just fall straight down.
Newton had a bit to say about all this.
If it was something heavy like a canonball it wouldnt get buffeted so much and literaly just fall straight down.
Newton had a bit to say about all this.
ferrisbueller said:In my experience its not enough to hold it up - it'll still drop to the ground.
If I stood at the back door of a train travelling at 70mph through a station and threw a ball directly behind the train at 70mph,what would an observer on the platform see?Would he see the ball just drop to the ground or would something else happen?
Barring some minute relativistic correction, or aerodynamic interference from the air dragged along by the train etc. etc. he would see it drop.
What about air resistance on the ball?
victormeldrew said:
If I stood at the back door of a train travelling at 70mph through a station and threw a ball directly behind the train at 70mph,what would an observer on the platform see?Would he see the ball just drop to the ground or would something else happen?
Barring some minute relativistic correction, or aerodynamic interference from the air dragged along by the train etc. etc. he would see it drop.
What about air resistance on the ball?
Very good sir.
Kiwi XTR2 said:Ah yes, but the bullets would already be traveling at the same speed as the plane - firing them would give them additional kinetic energy and they would accelerate away from the plane as normal...
He also said, although nobody knew what it meant at the time - "Forward facing guns are not a good idea on a SR-71"
AJLintern said:They might "speed" away but they won't "accelerate" away (after reaching muzzle velocity) . . .
He also said, although nobody knew what it meant at the time - "Forward facing guns are not a good idea on a SR-71"
And then they would decelerate dramatically while the Blackbird would not
Another one to ponder.
A train is trundling down a track at 30mph. It hits a fly which is travelling from the opposite direction at 30mph. The fly is squashed on the front of the train.
The fly is decellerated from 30mph to -30mph. At some stage the fly must be doing 0mph and since the train is in contact with the fly does this mean the train has also slowed to 0mph?
A train is trundling down a track at 30mph. It hits a fly which is travelling from the opposite direction at 30mph. The fly is squashed on the front of the train.
The fly is decellerated from 30mph to -30mph. At some stage the fly must be doing 0mph and since the train is in contact with the fly does this mean the train has also slowed to 0mph?
esselte said:
If I stood at the back door of a train travelling at 70mph through a station and threw a ball directly behind the train at 70mph,what would an observer on the platform see?Would he see the ball just drop to the ground or would something else happen?
I think you'd probably get shot by the police.
rsvmilly said:
Another one to ponder.
A train is trundling down a track at 30mph. It hits a fly which is travelling from the opposite direction at 30mph. The fly is squashed on the front of the train.
The fly is decellerated from 30mph to -30mph. At some stage the fly must be doing 0mph and since the train is in contact with the fly does this mean the train has also slowed to 0mph?
No, because the fly wouldn't decellerate, it would be doing 30 in one direction and then 30 in the other, well, parts of it would :P
rsvmilly said:
Another one to ponder.
A train is trundling down a track at 30mph. It hits a fly which is travelling from the opposite direction at 30mph. The fly is squashed on the front of the train.
The fly is decellerated from 30mph to -30mph. At some stage the fly must be doing 0mph and since the train is in contact with the fly does this mean the train has also slowed to 0mph?
NO
all that happens is that the train experiences the same (but opposite direction) force as the fly does (F=ma). but because the train is marginally heavier than the fly its decelleration is less.
Kiwi XTR2 said:Yes well of course they would stop accelerating once they leave the barrel of the gun, but that's just being pedantic!
He also said, although nobody knew what it meant at the time - "Forward facing guns are not a good idea on a SR-71"
And then they would decelerate dramatically while the Blackbird would not
They would be going faster than the plane for a period and would be dropping at the same time as deccelerating. By the time the plane catches up they would be somewhere below it (unless you aimed them up a bit so that they managed to hit the plane on their way down, but that wouldn't be very clever!)
speedychrissie said:Ah, but what would be the last thing to go through the fly's mind?
Another one to ponder.
A train is trundling down a track at 30mph. It hits a fly which is travelling from the opposite direction at 30mph. The fly is squashed on the front of the train.
The fly is decellerated from 30mph to -30mph. At some stage the fly must be doing 0mph and since the train is in contact with the fly does this mean the train has also slowed to 0mph?
NO
all that happens is that the train experiences the same (but opposite direction) force as the fly does (F=ma). but because the train is marginally heavier than the fly its decelleration is less.
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