Question

Read the lab procedure for a controlled experiment that looks at the effect of heat on the circumference of bicycle tires.

Step 1: Pump up six identical bike tires to the recommended air pressure.
Step 2: Place three tires under heat lamps, and keep the other three tires at room temperature.
Step 3: After four hours, measure the circumference of each tire.
Step 4: Record your results in the table.
Step 5: (?)

Which step should be next in this procedure?
List the materials that are needed.
Write a conclusion for the experiment.
Write a hypothesis for the results.
Draw a table for the observations.
Mark this and return

Answer 1

Which step should be next?
- Step 5: Analyze the data and draw a conclusion. (Calculate the average circumference for the heated group and the control group, compare them, make a graph, and assess whether any difference is large enough to support your hypothesis. Optionally perform a simple statistical test or report measurement uncertainty.)

(Also: for a stronger experiment, add an initial measurement step before heating — i.e., measure and record each tire's circumference right after pumping and before placing them under lamps — so you can compare before-and-after changes.)

Materials needed
- 6 identical bicycle tires (mounted on identical rims)
- Tire pump with pressure gauge (or a separate tire pressure gauge)
- 3 heat lamps (with stands) and power source
- Thermometer(s) (to monitor lamp temperature and room temperature)
- Measuring tape or flexible cloth tape measure (accurate to mm)
- Marker or labels to identify each tire (1–6)
- Stopwatch/timer (to time 4 hours)
- Notebook or data sheet and pen/pencil (or a computer spreadsheet)
- Safety equipment (gloves, eye protection, heat-resistant surface)
- Ruler/caliper (optional, for more precise measurements)
- Camera (optional, to photograph setup and measurements)

Hypothesis
- If bicycle tires are heated, then their circumference will increase, because heating the air inside the tire will cause the air to expand and raise the internal pressure slightly, stretching the tire and increasing its circumference.

Conclusion (general template tied to results)
- If the heated tires show larger circumferences than the control tires: The results support the hypothesis. The average circumference of the tires exposed to heat was greater than that of the room-temperature tires, indicating that heating caused the air inside the tire to expand and slightly increase the tire's circumference.
- If there is no measurable difference: The results do not support the hypothesis under these conditions. Any change was within measurement uncertainty, so either the temperature change was insufficient to produce a measurable expansion or the tire material constrained circumference change.
- Include in your conclusion: the numerical comparison (group averages and spread), possible sources of error (uneven heating, leaks, measurement error, differences in tire/rim manufacture), and suggestions for improving the experiment (measure initial circumference, increase temperature difference, repeat trials, use more sensitive measuring tools, perform statistical test).

Table for observations
Use this table to record each tire and then compute group averages.

Tire ID | Condition | Initial circumference (cm) | Final circumference (cm) | Change (cm) | Notes
------- | ------------- | -------------------------- | ------------------------ | ----------- | -----
1 | Heated | | | |
2 | Heated | | | |
3 | Heated | | | |
4 | Room temp | | | |
5 | Room temp | | | |
6 | Room temp | | | |
Average (heated group) | | | | |
Average (room temp) | | | | |

(If you did not measure initial circumference, leave that column blank and use the "Final circumference" values for comparison. Add rows for standard deviation or measurement uncertainty if desired.)

Marked complete and returned.