Have you ever wondered why some objects float, and ... - Quia



Floating and Sinking Objects Name:_____________

In this activity, you will measure and compare the properties of floating and sinking objects.

Part I: Collecting the Data - To begin, practice using the Graduated Cylinder and Scale to measure the mass and volume of the objects displayed on the shelves.

A. Notice that when you mouse over the items, they are numbered. Drag the small red cone (object 1) onto the Scale. What is the mass of the cone? What unit is used for mass? Record the mass on the data table below.

B. Now drop the red cone into the Graduated Cylinder. The amount that the water rises, called the displacement of the water, gives the object's volume. The displacement is displayed above the Graduated Cylinder. What is the volume of the small red cone? Record the volume on the data table below.

C. Check that the Liquid Density (g/mL) is set to 1.0, and drag the red cone into the Beaker of Liquid. Does the cone sink or float? Record the results.

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D. Using the Gizmo, fill in the remainder of your data table, except for the last column. How many objects floated? _____ How many sank? _____

Part II: Analyzing the results

1. Compare the Mass values to the floats or sinks values.

A. In general, did most of the items with high masses sink or float? ________ Were there any exceptions to this? ______

B. Did any of the most massive objects float? _____ Did any of the least massive objects sink?_____

C. Based on your results, is mass alone enough to determine if an object will sink or float? Explain your reasoning.

2. Now compare the Volume values to the results of the floatation experiment.

A. In general, how did the volume affect whether the objects sank or floated? ______________________________________________

B. Were there any exceptions to this?_____ Did any of the smaller items float?_____ Did any of the largest objects sink? _____

3. Now look at the Mass and Volume of each object.

A. What did all of the floating objects have in common? ______________________________________________________

B. What did all of the sinking objects have in common? ______________________________________________________

C. Based on your data, write a general rule to determine if an object will sink or float. _____________________________________________________________________

4. Label the last column in your data table Density. Use a calculator (F12) to find the density of each object, and complete your data table. For solids, the density is usually reported in g/cc. Remember: Density = mass / volume

A. What do you notice about the density of all of the sinking objects? ______________________________________________________

B. What do you notice about the density of all of the floating objects? ______________________________________________________

5. In the third century BCE, King Hieron II of Syracuse (in Greece) commissioned a goldsmith to make him a crown of pure gold. When he received the crown, however, the king suspected the goldsmith of pocketing some of the gold for himself, and substituting silver or brass into the crown. He had no way to prove this until the mathematician Archimedes solved the problem.

A. Use the Gizmo to calculate the density of each crown.

Remember: Density = mass / volume

Show your work!!

Crown A: Crown B: Crown C:

B. Pure gold has a density of 19.3 g/cc. Which of the crowns are pure gold? _______

Which are fakes?____________

C. Archimedes knew how to find the mass of the crown. His challenge was to find the volume of such an irregularly–shaped object. He solved the problem while getting into his bathtub, then famously ran naked through the streets shouting "Eureka!" Based on what you have observed in the Gizmo, what do you think Archimedes saw when he got in the bath?

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