1. Density

2. Drill
Which type of emergency drill would Ms. Massella announce over the PA system if we had an earthquake?
Where is our secondary evacuation location if we have a serious fire, or emergency drill, in the building?

3. Objectives iWBAT Show mastery of safety rules on a safety quiz.
predict whether an object has a higher or lower density than water.
solve density problems.
Perform a density lab to determine the density of an object.

4. Do you know the density of water?
What is the density of “pure” water?
The density of water is 1 g/ml

5. Sink or Float Does a cork sink or float in water ?
Is the density of a cork more or less than
1 g/ml ?

6. Density Equation
Do you remember what the Density equation is from the Accuracy/Precision lab?
Density = _mass____
volume
What are the units used for mass?
What are the units used for volume?
What would be the units for density?

7. Let’s try some problems.
Set up the equation and solve for density.
The mass of an object is 6.5g and the volume is 4.8 ml, what is the density of the object?
Ans: 1.35 g/ml

8. Let’s try some problems.
Solve for density.
The mass of an object is 1.09 g and the volume is 3.72 ml, what is the density of the object?
Ans: 0.29 g/ml

9. Let’s try some problems.
Set up the equation and solve for mass.
The density of an object is 5.12 g/ml and the volume is 7.07 ml, what is the mass of the object?
Ans: 36.2 g

10. Let’s try some problems.
Solve for mass.
The density of an object is 1.11 g/ml and the volume is 2.55 ml, what is the mass of the object?
Ans: g

11. Let’s try some problems.
Set up the equation and solve for volume.
The density of an object is 10.2 g/ml and the mass is 4.99g, what is the volume of the object?
Ans: ml

12. What happens if the object is a cube or rectangle?
Instead of using ml that you read off of a graduated cylinder, you can find the volume of the object by measuring with a meter stick.
Do you remember how to determine the volume of a cube?
Length x width x height

13. Cube volume units
If you use length x width x height to determine the volume, what will the units be?
The units will be cm3
Note: If you multiply the numbers, you also need to multiply the units.
Ex: 3 cm x 2 cm x 1 cm = 6 cm3

14. Practice Problem Set up the equation and solve for volume.
The density of block of metal is 0.65 g/cm3 and the mass is 2.47g, what is the volume of the object?
Ans: cm3

15. Density Practice Problems
Pick up a copy of the Density worksheet.
Try working out the problems.
Remember to show all of your work.

16. Wrap Up
I will switch to the Sink or Float ppt.