Which four physical forces are the forces of flight?

Which four physical forces are the forces of flight?

• A. Airspeed, Altitude, Temperature, Humidity
• B. Push, Pull, Gravity, Lift
• C. Lift, Drag, Weight, Thrust
• D. Lift, Drag, Pressure, Buoyancy

Answer: (C)

Four forces govern flight: lift, weight, thrust, and drag. Lift is the upward force produced by the wings as air flows over and under them. Weight is the downward pull of gravity. Thrust is the forward force generated by the engines or propellers, pushing the aircraft through the air. Drag is the backward resistance from air as the airplane moves. In steady, level flight, lift exactly balances weight and thrust exactly balances drag, so the aircraft stays at the same altitude and speed. If you climb, thrust and/or lift increase relative to drag and weight; if you descend, the opposite happens. The other options mix things that aren’t forces of flight. Environmental factors like airspeed, altitude, temperature, and humidity aren’t forces themselves. Push and pull describe forces in a general sense but don’t specify the aviation forces, and they omit thrust. Pressure and buoyancy aren’t the four flight forces (though pressure differences contribute to lift, buoyancy is negligible for airplanes).

Four forces govern flight: lift, weight, thrust, and drag. Lift is the upward force produced by the wings as air flows over and under them. Weight is the downward pull of gravity. Thrust is the forward force generated by the engines or propellers, pushing the aircraft through the air. Drag is the backward resistance from air as the airplane moves.

In steady, level flight, lift exactly balances weight and thrust exactly balances drag, so the aircraft stays at the same altitude and speed. If you climb, thrust and/or lift increase relative to drag and weight; if you descend, the opposite happens.

The other options mix things that aren’t forces of flight. Environmental factors like airspeed, altitude, temperature, and humidity aren’t forces themselves. Push and pull describe forces in a general sense but don’t specify the aviation forces, and they omit thrust. Pressure and buoyancy aren’t the four flight forces (though pressure differences contribute to lift, buoyancy is negligible for airplanes).