In order for an aircraft to take off, which two forces must be sufficient?

For an aircraft to successfully take off, it must generate enough thrust to propel it forward and produce enough lift to overcome its weight. Thrust is the forward force created by the engines, which propels the aircraft down the runway. Lift, on the other hand, is generated by the wings as air flows over and under them, allowing the aircraft to rise off the ground.

When the thrust exceeds the drag force (which opposes the aircraft's motion), the aircraft accelerates. As the speed increases, the airflow over the wings enhances the lift until it reaches a level sufficient to overcome the gravitational pull (weight) acting on the aircraft. At the point when lift equals or exceeds weight, the aircraft can take off.

Other choices do not accurately reflect the necessary forces for takeoff. For instance, weight is a force that the aircraft must overcome with lift to ascend, and drag is also a force that slows the aircraft down, making it essential to have sufficient thrust to counteract it, but it is not a required force for takeoff on its own.