why does an ball pen does not write when it is written upside down?

Answer 1

gravity is necessary for ink to come out from that pen

Answer 2

It's probably because ball pen ink is a thick fluid and the pen is made in such a way that the falls on air pressure and not on gravity. That's why a pencil works better than a pen in space as the air pressure is comparitively low and there is'nt any gravity too. When you tilt the pen upside down the weight of the pen supresses the air pressure but you should see that only some times the pen will work when written upside down.

Answer 3

Because in the ball pen the ball is located in between the ink reservoir and the paper by a socket, and while it's in tight, it has enough room to roll around as you write. As the pen moves across the paper, the ball turns and gravity forces the ink down the reservoir and onto the ball where it is transferred onto the paper. It's this rolling mechanism that allows the ink to flow onto the top of the ball and roll onto the paper you're writing on, while at the same time sealing the ink from the air so it does not dry in the reservoir.
Because the tip of a normal ballpoint pen is so tiny, it is hard to visualize how the ball and socket actually work. One way to understand it clearly is to look at a bottle of roll-on anti-perspirant, which uses the same technology at a much larger scale! The typical container of roll-on has the same problems a ballpoint pen does -- it wants to keep air out of the liquid anti-perspirant while at the same time making it easy to apply. At this scale it is easy to see how the mechanism works. Here's a shot of the ball end of a typical roll-on:

Answer 4

A normal, gravity fed pen doesn't write upside down; a Fisher Space Pen DOES write upside down and sideways. NASA uses them.

Answer 5

When it is the right way up the ink needs to flow down to the ball as you use it up. When you write upside down the ink flows away from the ball.

Answer 6

This question reminds me of the story of the U.S. government spending millions of dollars to develope a pen that would write in space so that the astronauts could keep notes in a gravity free environment. The Russians solved the same delema for about 15 cents - they used a pencil.

Answer 7

When upside-down, gravity pulls the ink away from the ball.

Answer 8

They sell pressurized ball pen cartridges that can write ups side down. This was developed by NASA. The first commercial brand was Fisher.

Answer 9

It relies on gravity to push the ink down through the ball part.

Answer 10

u need gravity to pull down de ink, heard the nasas hav been investing millions trying to develop a pen dat writes in space and when they succeed wif triumph they realise dat the russias hav been using pencils

Answer 11

it is a matter of gravity as it pushes the ink in an opposite direction so the pen writes with difficulty or sometimes doesn't write.