Final answer:
To measure the speed of a hummingbird's wingbeats, a scientist would use seconds as the fundamental unit, with milliseconds (10^-3 seconds) for precision, corresponding to the 'milli' metric prefix.
Step-by-step explanation:
To measure the speed of a butterfly wing, velocity is the appropriate metric. However, when considering the question which discusses a hummingbird's wing beats, the scientist should use the fundamental unit of seconds to measure the time it takes for a hummingbird to beat its wings once. Because hummingbird wings can beat very quickly, more than 50 times per second, the scientist will likely measure this duration in milliseconds, which is 10-3 seconds, to capture the rapid movement precisely.The metric prefix corresponding to 10-3 is 'milli', hence the time between each wingbeat could be expressed in milliseconds. For example, if a hummingbird is beating its wings 50 times per second, this would correspond to 20 milliseconds per wing beat, which highlights why such a precise measurement unit is needed.