(b) An automobile speedometer with circular scales reading both miles per hour and kilometers per hour is shown. What speed is indicated, in both units? How many significant figures are in the measurements?

Verified step by step guidance

1. <Examine the speedometer and identify the needle's position on both the miles per hour (mph) and kilometers per hour (km/h) scales.>
2. <Read the speed indicated on the mph scale. Note the number of digits that are certain and the first uncertain digit to determine the number of significant figures.>
3. <Read the speed indicated on the km/h scale. Again, note the number of digits that are certain and the first uncertain digit to determine the number of significant figures.>
4. <Compare the readings from both scales to ensure consistency and accuracy in the conversion between mph and km/h.>
5. <Summarize the speed readings in both units and state the number of significant figures for each measurement.>

Key Concepts

Units of Measurement

Understanding units of measurement is crucial in chemistry and physics, as they provide a standard way to quantify physical quantities. In this case, miles per hour (mph) and kilometers per hour (km/h) are both units of speed, allowing for the comparison of rates of motion. Converting between these units may be necessary depending on the context of the problem.

Significant Figures

Significant figures are the digits in a number that contribute to its precision. This concept is essential in scientific measurements, as it indicates the certainty of the data. When reporting measurements, the number of significant figures reflects the precision of the measuring instrument and the reliability of the data, which is important for accurate scientific communication.

Conversion Factors

Conversion factors are ratios used to convert one unit of measurement to another. In the context of speed, knowing the conversion factor between miles and kilometers (1 mile ≈ 1.60934 kilometers) allows for accurate translation of speed readings from one unit to another. Mastery of conversion factors is vital for solving problems that involve different measurement systems.