Stuck Together (Funky Physics Experiments)

You will need:

1. 2 identical drinking
   glasses (preferably
   plastic, so they don’t
   break in case they fall)
2. Tissue paper
3. Hot water

Simply stick two drinking glasses together with nothing else but hot air. Follow the instructions.

INSTRUCTIONS

1. Take some hot water and pour it into each of the two plastic glasses, until the glasses are half full.
2. Swish the water around gently. Be careful
   not to burn yourself.
3. Take your tissue paper and soak it in the hot water. Do not scrunch it.
4. Empty out the hot water from both the glasses after a minute or two.
5. Take your soaked tissue paper and let it lie flat over the rim of one of the empty glasses.
6. Place the other empty glass upside down over the tissue-covered glass.
7. Press on the overturned glass gently. Wait for a few minutes.

RESULT

After a few minutes, try picking up the overturned glass. You should be able to lift both the glasses, since they are now both stuck. This is a result of the hot water which is poured inside the glasses. The hot water leads to an increase in temperature which increases the air pressure inside the glass. However, after the damp tissue and second glass are placed over the empty glass, the temperature inside the glasses falls, leading to a decrease in air pressure as well. Now since the air pressure outside the glasses is higher than the pressure inside the glasses, it pushes the glasses towards each
other, sticking them together.