In researching the forces that act on flying birds, scientists studied the motion of cockatiels' bodies as they fly in horizontal flight. As the birds beat their wings, their bodies move up and down. (Figure 1) shows the vertical acceleration of a cockatiel's body during one wing beat, consisting of an upstroke followed by a downstroke. The bird is held in level flight due to the force exerted on it by the air as the bird beats its wings. What is the maximum value of this force due to the air? Note that the bird's weight, the force of gravity acting on it, is calculated using w=mg.