When Pacific parrotlets fly within a truck, the truck becomes lighter, by an amount equal to the weight of the birds, as their wings rise. The truck becomes heavier, by twice the weight of the birds, on the downbeats.
When Pacific parrotlets fly within a truck, the truck becomes lighter, by an amount equal to the weight of the birds, as their wings rise. The truck becomes heavier, by twice the weight of the birds, on the downbeats.
