This week we completed an investigation called disco fruit, we made predictions measured our solutions and prepared our equipment. For our method we added bicarbinate soda with warm water and stired until it dissolved. Then we added a handful of dried fruit and white vinegar, the fruit began to float to the top and sink as if they were dancing. We discovered that when the bicarbinate soda and white vinegar mix they create a gas, the gas bubble attaches to the fruit and it floats to the top, when it meets the cool air it pops and it sinks to the bottom, thus giving the impression of it floating.
The ice lifter
Big question can you lift an ice cube with a piece of thread? We made predictions then investigated this question, trying various techniques such as trying to make a hole in the ice or melting the ice using heat. None of our ideas worked, then we discussed how we melt ice on a winter’s day, we thought of salt.
Here’s our method
- Put the thread across the ice cube.
- Lift the thread off the ice cube, we found it doesn’t move.
- Put the ice across the thread again.
- Pour the salt on to the ice cube so that it covers the thread.
- Wait a few seconds.
- Now, take hold of each end of the thread and lift up the ice cube.
We discussed how we could make our method more accurate by specifying a measurement but then concluded the ice would have to be the same size too.
What we found out
The salt melts the ice on the top of the ice cube, making a small puddle of water. The rest of the ice cube is still very cold, so the water quickly freezes again around the thread. The thread is now stuck to the ice, so you can lift it up!
Capillary action - walking water
- 5-10 drops of red food coloring to glass 1 and 7
- 15 drops of yellow food coloring to glass 3
- 5-10 drops food coloring to glass 5
- A bottle of water
- vegetable oil
- food colouring
- Fill bottle 2/3 with water
- Add a few drops of food colouring
- Fill the bottle rest of the way with vegetable oil, leaving a bit of space at the top
- Add in a table spoon of salt on to the oil- The first bubbles form as the salt sinks and releases air bubbles. Once it reaches the bottom, oil blobs move as the salt sinks and releases air bubbles.
- add more salt to repeat the effect.
How it works
The homemade lava lamp works because oil is less dense than water and floats on top of it. Salt is more dense than either oil or water, so it sinks when you add it to the bottle. Oil blobs stick together and slowly return to the top of the glass.