TDV ROUND 2: Dabbling with Density! NAME: SECTION:

Transcription

1 TDV ROUND 2: Dabbling with Density! NAME: SECTION:

2 DEMO: EGGIES UP, EGGIES DOWN Diagrams: (clearly labeled) Quick Conclusion: DEMO: SUNKEN ICE CUBES Diagrams: (clearly labeled) Quick Conclusion:

3 DEMO: FLOATING SPHERES Question: What will happen if 30 ml of rubbing alcohol (dyed green) is added to 50 ml of water (dyed red)? What will happen if drops of vegetable oil are then dropped into the alcohol and water? 2 Hypotheses: Evidence Collection & Results Diagrams: (clearly labeled) Observations: Quick Conclusion:

4 DEMO: RETRO TWIN Question: What will happen if 50 ml of vegetable oil is added to 450 ml of water (dyed red)? What will happen if salt is then sprinkled on top of the oil and water? 2 Hypotheses: Evidence Collection & Results Diagrams: (clearly labeled) Observations: Quick Conclusion:

5 DEMO: LIQUID LAYER CAKE Objective: To accurately predict the relative density of a number of materials and then arrange the materials in a liquid layer cake according to their densities. Materials: salt water (dyed orange) steel Pepsi soda cork water (dyed red) rubber vegetable oil air rubbing alcohol (dyed green) wood glycerin corn syrup Dawn dish soap (blue) Methods: Approximately 30 ml of each liquid will be added to a 500 ml glass graduated cylinder. The liquid predicted to be the most dense will be added first. All solids will be added last. Instructions: Please write the name of the materials in order of their densities. The least dense material should be written in the #1 blank; the most dense material should be written in the #13 blank. PREDICTED ACTUAL Difference #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13

6 BUBBLEOLOGY PREP Prep Questions (at least 2 complete sentences for each) 1) Please describe a bubble and how a bubble behaves in liquid. (Think of carbonated soda.) 2) Think of the bubbles that are made when mixing a saturated baking soda solution with vinegar (the volcano experiment!). Where do the bubbles come from? What are they made of? (Take a guess or look it up!) 3) Do all bubbles have gas inside them? Why do you think this? 4) Could bubbles have something else inside them (liquid or solid)? Why do you think this? 5) Please predict: What will happen when you put the ice in the yellow fluid? Why? 6) Please predict: Will the ice float or sink? Why?

7 BUBBLEOLOGY Materials & Methods Materials Methods ml graduated cylinder Place the ice cube in 100 ml of mysterious yellow liquid the graduated cylinder 1 ice cube (dyed green) filled w/ yellow liquid 1 pair of tongs and record the results. Evidence Collection & Results Diagrams: (clearly labeled) Observations: Concluding Questions (at least 2 complete sentences for each) 1) Why did the ice behave the way it did? 2) What was at the bottom of the cylinder? Why was this material at the bottom of the cylinder? 3) How could you make the ice cube move to a different part of the cylinder (either up or down, depending on where the ice is at the beginning)?

8 FLINKHOOD PREP Prep Questions (at least 2 complete sentences for each) 1) Explain what the words float and sink mean to you. 2) Can you accurately predict whether or not an object will float before you put the object in water? Why or why not? 3) Does the size of an object matter when determining whether or not the object will float? Why? Use specific examples to support your theories. 4) Does the mass of an object matter when determining whether or not the object will float? Why? Use specific examples to support your theories. 5) Please predict: Will putting rocks into your flinker help the device to sink? Why or why not? 6) Please predict: Will putting pieces of dry wood into your flinker help the device to float? Why or why not?

9 STRIVING FOR FLINKHOOD! Objective: To create a device that will achieve Flinkhood. Flinkhood is a magical state of neither floating nor sinking. You will use a corked test tube as your flinker device and try to get it to hover in the middle of a 250 ml graduated cylinder filled with water. In order to qualify for Flinkhood, the top of your flinker needs to be visibly below the surface of the water and the bottom of your flinker needs to be visibly above the bottom of the graduated cylinder for at least 20 seconds. Materials & Methods Materials: 1 16 mm x 150 mm glass test tube 1 cork 2 10 ml graduated cylinders ml graduated cylinder ~252 ml of water (~240 ml for inside the g.c., ~12 ml for inside the test tube) any amount of salt, plastic beads, wooden toothpicks, foam, metal brads, or pebbles Methods: Each flinker MUST have exactly 12 ml of water inside of it both before and after the test. Each flinker must have a cork. Nothing can be attached to the outside of the test tube. All items must be added to the inside of the test tube. The test tube may not be attached to the graduated cylinder in any way. The rest is up to you! Evidence Collection Please list your trials below. Write float or sink next to each entry; note how long the flinker took to travel to the surface or to the bottom. ex. 2 toothpicks float (3 sec)

10 If you achieved Flinkhood, proceed as follows: 1) Please measure the mass of your flinker. Zero your balance. Be as precise as possible! Make sure the outside of your flinker is completely dry before weighing it. 2) Please measure the volume of your flinker. Use a 100 ml graduated cylinder, fill it to exactly 65 ml, and then use the displacement method. Be as precise as possible! Make sure the outside of your flinker is completely dry before measuring it. 3) Please calculate the density of your flinker. (Box your answer.) 4) What is the density of water? 5) Why did your flinker achieve Flinkhood?