## as fast as a speeding bullet

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• If a bullet were fired from a gun pointed horizontally across a horizontal plane at the same instance that another bullet were dropped from the same height.
Message 1 of 6 , Jul 1, 2002
If a bullet were fired from a gun pointed horizontally across a horizontal plane at the same instance that another bullet were dropped from the same height. Which bullet would hit the ground first.

A glass marble is in a small dish that is floating in a larger dish of water. If the marble is taken out of the small dish and dropped in the water, what would happen to the water level?

A lump of (water) ice is in a small dish that is floating in a larger dish of water. If the ice is taken out of the small dish and dropped in the water, what would happen to the water level?

What would happen to the water level when the ice cube melted?

An ice cube is held under-water (by a net for example), What happens to the level of the water when the ice cube melts?

A train is travelling at 100 mph. A fly is flying directly towards the train at 5 mph and it hits the windscreen of the train. The fly has changed speed and direction from +5mph to -100mph. At some point the fly must have passed through zero mph. At that instance the fly must have been in contact with the train so the train must also have been at zero mph. ergo the fly (momentarily) stopped the train?

As a side question, what was the last thing to go through the flys mind when it hit the train?

Have fun
Ian

• 1)By law of gravity... because both the bullets will be under free fall both of them must touch the ground simultaneously(If air friction is neglected). 2)The
Message 2 of 6 , Jul 1, 2002
1)By law of gravity... because both the bullets will be under free fall both of them must touch the ground simultaneously(If air friction is neglected).
2)The water level would decrease
3)The water level would remain the same...even after melting
4)The water level would remain the same as it was when the ice was held  by the net.
5)The fly or the train are never at 0km/sec because they always travel a distance however small in any duration of time.The fly changes the direction of its motion owing to the acceleration in the opposite direction by the train.Even though the fly has a velocity changing from 5 to -100 it can never be said that the fly stays at 0km/sec because it would be analogous to saying " One can never cross 1 meter because in order to do so u need to cross 1/2 meter...for that u have to cross1/4 meter....and so on...the series never ends...But in practice we now this isn't true!"
I would love to hear the explaination  given to this problem
Bye

-----Original Message----
From: ian [mailto:ian@...]
Sent: Tuesday, July 02, 2002 1:34 AM
To: puzzles@yahoogroups.com
Subject: [puzzles] as fast as a speeding bullet

1) If a bullet were fired from a gun pointed horizontally across a horizontal plane at the same instance that another bullet were dropped from the same height. Which bullet would hit the ground first.

2) A glass marble is in a small dish that is floating in a larger dish of water. If the marble is taken out of the small dish and dropped in the water, what would happen to the water level?

3) A lump of (water) ice is in a small dish that is floating in a larger dish of water. If the ice is taken out of the small dish and dropped in the water, what would happen to the water level?

What would happen to the water level when the ice cube melted?

4) An ice cube is held under-water (by a net for example), What happens to the level of the water when the ice cube melts?

5)A train is travelling at 100 mph. A fly is flying directly towards the train at 5 mph and it hits the windscreen of the train. The fly has changed speed and direction from +5mph to -100mph. At some point the fly must have passed through zero mph. At that instance the fly must have been in contact with the train so the train must also have been at zero mph. ergo the fly (momentarily) stopped the train?

As a side question, what was the last thing to go through the flys mind when it hit the train?

Have fun
Ian

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• Message 3 of 6 , Jul 2, 2002
<<If a bullet were fired from a gun pointed horizontally across a
horizontal plane at the same instance that another bullet were dropped
from the same height. Which bullet would hit the ground first.>>

I think that they: should land at the same time.

<<A glass marble is in a small dish that is floating in a larger dish of
water. If the marble is taken out of the small dish and dropped in the
water, what would happen to the water level?>>

I think that the water level would remain unchanged; but am not sure.

<<A lump of (water) ice is in a small dish that is floating in a larger
dish of water. If the ice is taken out of the small dish and dropped in
the water, what would happen to the water level?>>

Again, I think that it would remain unchanged.

<<What would happen to the water level when the ice cube melted?>>

Nothing

<<An ice cube is held under-water (by a net for example), What happens to
the level of the water when the ice cube melts?>>

Nothing

<<A train is travelling at 100 mph. A fly is flying directly towards the
train at 5 mph and it hits the windscreen of the train. The fly has
changed speed and direction from +5mph to -100mph. At some point the fly
must have passed through zero mph. At that instance the fly must have
been in contact with the train so the train must also have been at zero
mph. ergo the fly (momentarily) stopped the train?>>

No - for the short period of time when the fly was at speed 0 MPH, a very
small part of the train stopped and bent, probably rebounding after the
impact. Thus the impact does a lot of damage to the fly and a little
damage to the train.

<<As a side question, what was the last thing to go through the fly's
mind when it hit the train?>>

"Next time go by train, not at train."

LKG
• ... plane at the ... bullet would ... They would hit at the same time. ... water. If the ... happen to ... The water level would drop. In the dish the marble
Message 4 of 6 , Jul 2, 2002
>If a bullet were fired from a gun pointed horizontally across a horizontal
plane at the
>same instance that another bullet were dropped from the same height. Which
bullet would
>hit the ground first.

They would hit at the same time.

>A glass marble is in a small dish that is floating in a larger dish of
water. If the
>marble is taken out of the small dish and dropped in the water, what would
happen to
>the water level?

The water level would drop. In the dish the marble displaces an equal weight
of water but when dropped into the water it only displaces it's own volume.

>A lump of (water) ice is in a small dish that is floating in a larger dish
of water. If
>the ice is taken out of the small dish and dropped in the water, what would
happen to
>the water level?

It stays the same. Since ice floats it is less dense than water so in both
cases it displaces it's own weight.

>What would happen to the water level when the ice cube melted?

It stays the same.

>An ice cube is held under-water (by a net for example), What happens to the
level of
>the water when the ice cube melts?

It would fall. Since ice is less dense than water (it would normally float)
then when it is held under water it would displace more water than when it
melts.

>A train is travelling at 100 mph. A fly is flying directly towards the
train at 5 mph
>and it hits the windscreen of the train. The fly has changed speed and
direction from
>+5mph to -100mph. At some point the fly must have passed through zero mph.
At that
>instance the fly must have been in contact with the train so the train must
also have
>been at zero mph. ergo the fly (momentarily) stopped the train?

I don't know the answer to this but I have always believed that part of the
train would deflect or vibrate (hence the splat sound) so it is quite
possible that a small part of the train would also pass through zero mph.

>As a side question, what was the last thing to go through the flys mind
when it hit
>the train?

Its back-side! :O

Regards
Ian
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