• Graduated cylinder
• 2 marbles
• Liquids to test such as water, corn syrup, canola oil, motor oil • Masking tape
• 1 cm ruler
• Stopwatch that is accurate to 0.1 or 0.01 seconds
SAFETY NOTE: See Texas Science Safety Manual for lab and investigation guidelines: http://www.tenet.edu/teks/science/safety/safety_manual.html
Engagement: Place a wooden ramp on a stack of books. Challenge students to predict which of three liquids (syrup, water, and motor oil) will reach the bottom of the ramp first. Use one drop of each liquid. Have students write their predictions and observations in their science journals. Ask student to identify which property of matter is best represented by this demonstration.
1. Fill a graduated cylinder with one of the liquids (water, corn syrup, canola oil or motor oil), up to about 5 cm from the top.
2. Mark with tape a convenient starting point about 2 cm below the surface of the liquid (which will allow the sphere to reach terminal velocity before you begin making measurements). You can use either the top or the bottom of the tape, but use the same points for each measurement you make when you drop the spheres.
3. Mark an ending point about 5 cm from the bottom.
4. Measure the distance between the starting and ending points, and enter the answer in the data table as "Fall distance."
5. Drop the sphere into the liquid and start measuring time when the sphere reaches the first masking tape line. Stop measuring time when the sphere passes the second piece of tape. Repeat the time measurements for a total of 5 trials.
6. Clean the graduated cylinder and repeat procedure with other liquids. 7. Complete the data table by averaging the times for each substance. Use this time when calculating the speed of the sphere.