Speed of Bubble Lab

Purpose: The speed of the bubble tubes provide you with practice setting up experiments and graphing data.

Question: Which “bubble tube” will travel the fastest?

Hypothesis:

Safety: Follow proper lab behavior rules. Ask your teacher if you do not know these rules, or do not understand them. These tubes are breakable. Treat them with care. Tell your teacher immediately if a tube cracks, breaks, or leaks. Then you can take proper clean-up steps.

Procedure:

  1. Work with a partner. Select one color of tube to use. Later you will use the others.
  1. Find out how long it takes the bubble to rise from the bottom of the tube to the top, when the tube is held vertically.
  1. Now find the distance the bubble travels in various lengths of time. Follow these steps:
  2. Choose a time. The time should be at least 4 seconds, but shorter than the amount of time it takes the bubble to reach the top
  3. Hold the tube not quite horizontal, so the bubble is at one end.
  4. Your partner should be watching the clock. When your partner says “Start”, quickly turn the tube upright.
  5. Move one finger along the tube, keeping it next to the bottom of the bubble.
  6. When your partner says “Stop”, stop moving your finger.
  7. Keep your finger on this spot, while your partner measures the distance (to the tenth of a centimeter) from where the bubble began, to your finger.
  8. Record the time and distance in the data table.
  1. Repeat these steps 4 more times, using different lengths. Use a wide variety of times, including long and short times. You should have a total of 5 lengths and times.
  1. Now repeat the same steps, using the different colored tubes.
  1. Graph the data:
  2. Using a straight edge, draw a “best-fit line.” We should not expect the data points to all fall exactly on the line. It may be that none of them will. This is because all measurements contain uncertainty.
  3. The lines should go through the point (0,0).
  1. Conclusion:

Questions:

  1. What was the independent variable in this lab?
  1. What was the dependent variable in this lab?
  1. List at least 2 constant variables used in the lab.
  1. How far did the bubble in the green tube travel in 6.5 seconds? ______
  1. How far did the bubble in the red tube travel in 6.5 seconds? ______
  1. How far did the bubble in the blue tube travel in 6.5 seconds? ______
  1. In which tube was the bubble the fastest? ______
  1. Which tube had the steepest graph? ______
  1. Is there a connection between your answers to questions 7 and 8? Explain!

In the field of math, we often use the word “slope” when we want to use numbers to say how steep something is. Slope is defined as Rise divided by Run. Rise is a vertical measurement, and Run is a horizontal measurement.

  1. Find the slope of the graphed line from the red tube. Follow these steps:
  1. Mark 2 points on the line, and label them A and B. The points should be on the line, and far apart. Try to choose points that will make it easy to read the distance and time measurements.
  1. Point A corresponds to a distance of ______, and a time of ______.

Point B corresponds to a distance of ______, and a time of ______.

  1. Use your answers from part b above to calculate the rise and run:

Rise =______minus ______= ______.

Run =______minus ______= ______.

(Did you remember to include units of measurement in you work above?)

  1. Now calculate the slope:

Slope = Rise divided by Run = ______.

(Show work and units)

  1. Follow the steps for #1 above to find the slope of the green tube. Show Work!
  1. Follow the steps for #1 above to find the slope of the blue tube. Show Work!
  1. In the calculations above, you divided rise by run. The rise was a distance, and the run was a time. “Distance divided by time” is the formula for calculating ______.
  1. The slope of a distance vs. time graph is the ______of the moving object.
  1. Imagine an object that traveled at a steady speed, and then stopped and remained motionless for a while. Sketch the shape of the line that would result.
  1. Imagine an object that goes faster and faster as it travels. Sketch the shape of the line that would result.
  1. What feature of the graphs from this experiment shows that the bubbles traveled at constant speeds?