Will It Sink or Float

Will It Sink or Float?

Name:

Period:

Materials:

A = Baby oil D = Lamp oil (colored) Sandwich bags

B = Water with food coloring in it E = Syrup Scale

C = Cooking oil Graduated cylinders

Activity 1:

1. Determine the mass of the graduated cylinder and record the mass in the chart (be sure to include the appropriate units).

2. Add 10 ml of A to this graduated cylinder and record the mass on your chart.

3. Add solution A to the sandwich bag.

4. Repeat for solutions B, C, D, and E.

5. Fill in the chart.

Sample	Mass of graduated cylinder (g)	Mass of cylinder + solution (g)	Mass of Solution (g)	Volume of Solution (ml)	Density D= M/V (g/ml)
A = baby oil					1.059 g/ml
B = colored water					1.00 g/ml
C = cooking oil					0.910 g/ml
D = lamp oil					0.75 g/ml-0.85 g/ml
E = syrup					1.3 g/ml

1. List the solutions in order of density starting with the least dense.

Lamp oil

Cooking oil

Colored water

Baby oil

Syrup

2. Diagram using colors what you observed when all 5 solutions were in the bag.

What will likely happen is that the students will only observe 4 layers as two of the densities are very close to each other and are very difficult to differentiate. When they ask why they can only see 4 layers, you can have them look at their densities and see if they can come up with the answer.

3. Write a hypothesis for what you think would happen if you added another 10 mls of solution B to the bag.

I believe that if I added 10 additional milliliters of solution B to the bag it would cause the colored water layer to increase while the other layers would stay the same.

4. Add an additional 10 mls of solution B to the bag, was your hypothesis correct? Students can write what they observed.

5. Substances such as oil are less dense than water. If something is more dense than water it sinks and if the density is the same as water it mixes. Define density in your own words.

Density is how much mass something has in a given amount of space.

Density = mass per unit volume

Activity 2

Materials:

Pebbles Baby food jar Container of Water

1. Mark the water level on your container.

2. Drop the pebbles into the container of water one at a time, gently.

3. What happened to the pebbles? The pebbles sank to the bottom of the container.

4. Did the water level change? Yes

5. Remove the pebbles, note the water level and place the baby food jar into the water.

6. Describe what you observed. Be sure to include in your observation about the water level and the location of the baby food jar. The baby food jar floats in the water and the water level increased.

7. Open the baby food jar, add a pebble to the jar, close the jar and place it back into the water.

8. What happened to the jar? Be sure to include the location of the baby food jar and the water level. As pebbles are added the water level should increase and baby food jar should sink further into the water.

9. Repeat this process until the jar sinks.

10. Hmmm this is curious, why did the rocks sink when placed directly into the water but floated when they were inside the jar? This has to do with buoyant force. The rocks weight is greater than the water pressure. But not with the jar, the shape of the jar is a factor. The hollow shape displaces a large volume of water, causing the buoyant force and mass of the jar to be in balance. The overall density of the jar is less than the density of water.

11. What principle does this exercise model?

Archimedes’ principle

12. Does the shape of an object have any affect on whether it will sink or float? Yes, that is the reason why the jar didn’t sink with the pebbles in it.