Which materials float and which don’t?
An investigation to find out which of a range of materials will float and which will sink in water.
Equipment required:
An empty butter tub or other container
Some bluetac/plasticine/modelling clay
A piece of polystyrene
A marble
The cork from a wine bottle
A safety match or lollypop stick
An empty film case with the lid on
A paper clip
Some paper
Background:
Some materials naturally float whilst others naturally sink. Using the butter tub as a water container, your task is to find out which of the objects listed above will float and which will sink.
Once you know the answer to this, your challenge then is to find a way of making all the objects float!
Let’s guess what will happen:
1. Spread the materials out in front of you so you can see them all.
2. Pick up one of the materials and look at it closely, noting how heavy it is, its shape, and anything else that you think might affect its ability to float.
3. On the results-sheet below, write down what material you think the object is made from.
4. On the results-sheet below, write down what you think will happen when the material is placed in water. This is called making a “Prediction”
5. Repeat steps 2, 3 and 4 for all of the objects in the list.
Let’s do a test to see if we are right or wrong:
6. Fill the butter tub about three quarters full of water and place it on a table
7. Take the first object listed on the answer sheet and place it carefully on the water
8. Watch what happens when you let go of the object. Does it float or sink?
9. On the results-sheet below, record the result of your test.
10. Repeat steps 6 to 9 for all the objects in the list until you have completed the results-sheet.
Which materials float and which don’t?
Results Sheet
Object: Material Prediction Test Answers
Float or Sink?
Some bluetac/plasticine/modelling clay: Bluetac will _____________ in water
A piece of polystyrene: Polystyrene will _____________ in water
A marble: A marble will _____________ in water
The cork from a wine bottle: Cork will _____________ in water
A safety match or lollypop stick: A safety match will _____________ in water
An empty film case with the lid on: An empty film case will _____________ in water
A paper clip: A paper clip will _____________ in water
Paper: Paper will _____________ in water
Can we make all the objects float?
11. Put all the objects that floated to one side and spread out those that sank in front of you.
12. Carefully look at the objects and try to think of reasons why they actually sank. Consider what materials they are made from.
13. Now try to think of something you could do that would make each object float.
14. Record what you did on the results-sheet below.
Using the Archimedes Principle
Results Table
To make the ______________________float, I had to ______________________________________
To make the ______________________float, I had to ______________________________________
To make the ______________________float, I had to ______________________________________
To make the ______________________float, I had to ______________________________________
To make the ______________________float, I had to ______________________________________
To make the ______________________float, I had to ______________________________________
To make the ______________________float, I had to ______________________________________
To make the ______________________float, I had to ______________________________________
Extension activity for Key Stage 2
Using the Archimedes Principle
An investigation to learn a simple way of measuring the volume of an object.
Equipment required:
A measuring cylinder
A marble
A pencil
Background:
Archimedes was a Greek scientist who lived a long time ago. One day he jumped into his bath and noticed that the water level rose up. When he got out of the bath the water level went down. And when he got back in, up it went again. Suddenly, he realised that he could use this to measure the amount of space taken up by his body. This measurement is known as the “volume” and is measured in cm3 or litres. He was so excited, he jumped up in his bath and shouted “eureka” at the top of his voice. Now you will use his discovery to measure the volume of some of the objects you used earlier.
Let’s measure the volume:
1. Spread the materials out in front of you so you can see them all.
2. Fill the measuring cylinder about half full with water.
3. Look closely at the line made by the top of the water in the measuring cylinder. You will see it curves slightly. This is known as the meniscus.
4. Using the scale on the side of the measuring cylinder, measure where the lowest point of the curve meets the scale. This is your starting volume. Write it down.
5. Now take one of the objects that sank and carefully drop it into the measuring cylinder.
6. Look again closely at the line made by the top of the water in the measuring cylinder. You will see it has risen up.
7. Using the scale on the side of the measuring cylinder, measure where the lowest point of the curve meets the scale. This is your finishing volume. Write it down.
8. To work out the volume you must now use some maths. You must subtract the starting volume from the finishing volume.
The answer you get will be the volume of the object.
Volume of object = Finishing Volume – Starting Volume
9. Repeat steps 4 to 8 for a range of different objects and work out their volumes.
10. Record all your results in the table below.
Object: Finishing Volume Starting Volume Actual Volume
Additional Questions for Key Stage 2
1. How would you measure the volume of an object that floats?
2. What else might make the level of the water change?
REMEMBER TO CLOSE THIS WINDOW IF YOU HAVE FINISHED LOOKING!
© South Staffordshire Water 2006