1. Kupaa ni kitendo cha kufanya mwendo(movement ) kwenye hewa (air) kwa kutumia either wings, like birds, or through the use of aircraft such as airplanes, helicopters, or other flying machines.
2. Miongoni mwa kitu cha muhimu ili kitu kuweza kupaa ni LIFT (NGAZI)..... kwenye kupaa hewa (air) ndiyo inatumika kama ngazi...na ndiyo maana utaona hata Ndege(birds) wakipiga mbawa zao ili kutengeneza lift ya kuwafanya wapae,...
Birds flap their wings in a specific way called the wing beat, which creates a difference in pressure between the top and bottom of the wing. Above the wing, the pressure is lower than below the wing.....This creates lift, which raises the bird into the air!
3. Kitu kitarudi chini endapo:-
kitapoteza uwezo wa Ku generate lift,. Ambapo hapo zinaweza kutokea sababu tofauti tofauti,.mfano Ndege (bird) akipata shida kwenye mbawa yake moja hatoweza Ku generate lift kitu ambacho kitamfanya arudi chini.
(a) sababu nyingine ni kukosa umbo sahihi,.Kwa mfano mnyama kama Tembo hana umbo sahihi la kumfanya apae.
(b) Hali ya hewa, mf. Upepo mkali,..Upepo ukizidi sana huweza kupelekea kurudi chini kwa kiumbe au objects iliyopaa.