Describe a method that could be used to determine the speed of sound in air.

A common method to measure the speed of sound in air is as follows: 1. **Setup:** Two observers position themselves a large, known distance apart (e.g., 100 m), measured using a measuring tape or trundle wheel. 2. **Procedure:** One observer has a starting pistol or two wooden blocks. The other observer has a stopwatch. The first observer fires the pistol or claps the blocks together. The second observer starts the stopwatch when they *see* the smoke from the pistol or the blocks hitting, and stops it when they *hear* the sound. This is because light travels much faster than sound, so the time delay is almost entirely due to the sound's travel time. 3. **Calculation:** The speed of sound is then calculated using the formula: speed = distance / time. 4. **Accuracy:** To improve accuracy, the experiment should be repeated several times and a mean time calculated. The observers could also swap positions and average the results to account for any wind effects.