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"Silly question."

Ok say you're standing in a train. It's going..... oh I dunno 100mph.
For no reason what so ever you decide to jump up in the air.

Now.

Will you land in the same spot you jumped up from?

I don't have an answer, I actually want to know.

Boobs

Wookie wins the prize here. It's all about relative velocity, and is one of the easiest laws of physics to ignore. The old "if i jump of a crashing plane at the last second I'll be fine" routine. Of course, the plane is crashing at something approximating 200-300 miles per hour or more, so unless you can jump at the same speed, you're pancake.

Same with the inside/outside train thing. Inside, everything in the train is moving at the same speed as the train itself. If you jump, there is no horizontal air resistance in the opposite direction of the train, hence very little actual deceleration, and so you'll land in pretty much the same spot. On top of the train, as soon as you leave the surface, you'll have 100mph of wind resistance slowing you down, which will mean you are suddenly doing maybe 30mph less than the train, so it will start to move ahead of you, and you will land farther down the train.

Physics can be so interesting. I'm still waiting for the day when someone can invent something that counters or nullifies air resistance around an object.

No problem!

I knew physics would come in useful one day.

Still waiting on the algebra, though!

Cheers wookie, got here late and you answered for me. ta.

i always used to think about that, so i asked my old physics teach and she told me that its summit to do with gravity x speed etc

:-)

*Makes mental note to stop watching Scrapheap Challenge*

It all depends on how high you can jump. Inside a train, you'd land pretty much where you started from.

But imagine for a moment that you were on the roof of a moving train. The higher you jumped, the further back down the train you would land - assuming of course that you jumped straight up in the air, and not forwards.

You move at the same speed as the train while it is moving because of the friction between your feet and the surface of the train. When you jump, you no longer have the train pulling you along, so you begin to slow down due to the forces of gravity and atmospheric resistance.

On a normal small jump inside the train, the effect of these would be so small as not to make any difference. But if you were on the roof of the train and could jump, say, ten feet straight up in the air, you would actually move several feet back down the train.

The 'fly on a bus' example is similar. On a bus, with all windows closed, all the air is moving at the same speed, making the relatvie speed to the fly zero miles per hour. So, if a fly flies at 4mph normally, it would still only be travelling at 4mph on the bus if it was flying from the back of the bus to the front. Of course, to those outside the bus (if they could see it), it would be travelling faster.

But it's all relative to the viewpoint.

I'm also pretty confident that once on Scrapheap challenge (haha!) they had to drop bombs from a moving blimp they had made.

The presenter made a point of saying they would have to drop the bomb BEFORE they were above the target, as once the bombs is droped it moves in an arch shape forward, even though it's no longer attached to the blimp, it's still moving at that speed and will continue to move at that speed for a short time. Hard to explain, but you'd land in a different spot.

Here's my crazy view on this.

You are still moving while standing still on the moving train, obviously. So I reacon you would land in a different spot, whether it be from you rolling, or the short distance you moved while in the air.

Think of a car. You're driving along, sitting still but moving with a car. The car crashes and comes to a sudden stop. You're not wearing a seatbelt, so you continue to move and go straight through the front window.

That's what I think anyway. With absolutly no science at all to back it up.