Final answer:
The bird flying in a straight line at a constant velocity of 1m/s is experiencing balanced forces. This indicates that the lift, gravity, thrust, and air resistance acting on the bird cancel each other out, allowing the bird to maintain its velocity without acceleration.
Step-by-step explanation:
If a bird is flying to the left at a constant speed of 1m/s without changing its speed or direction, then the forces acting on it are balanced. In physics, according to Newton's first law of motion, an object in motion will stay in motion with the same velocity unless acted upon by an unbalanced force. Since the bird is maintaining a constant velocity, there is no net acceleration, indicating that all forces acting on the bird, such as lift, gravity, drag (air resistance), and thrust (from the bird's flapping wings), are in equilibrium.
Gravity pulls the bird towards Earth, but this is counteracted by the lift generated by its wings. Similarly, any forward thrust produced by the bird's wings is matched by the drag from air resistance. When these forces are equal but opposite, they cancel each other out, and the bird flies at a constant velocity without accelerating.