4. In 1979, Bryan Allen pedalled the Gossamer Albatross aircraft 35.0 km across the English Channel in a time of 2.80 h. Calculate the average speed of the aircraft in m/s.

1. **Convert km to meters:** 35.0 km * 1000 m/km = 35000 m<br /><br />2. **Convert hours to seconds:** 2.80 h * 60 min/h * 60 s/min = 10080 s<br /><br />3. **Calculate average speed:** Speed = Distance / Time = 35000 m / 10080 s = 3.47 m/s (approximately)<br /><br />Therefore, the average speed of the aircraft was approximately $\boxed{3.47}$ m/s.<br />