Video narration
Kya rocket ko aage badhne ke liye hawa ko peeche dhakelna padta hai? Nahi. Gubbare ko chhodiye: hawa peeche nikalti hai, aur gubbara aage bhaagta hai. Rocket bhi yahi karta hai, woh apna indhan saath le jata hai. Engine garam gas ko tezi se peeche fenkta hai. Gas peeche jati hai, to rocket aage badhta hai. Yahi Newton's third law hai: har kriya ki barabar, ulti pratikriya. Ise thrust kehte hain. Indhan ghate to rocket halka hota hai, isliye wahi thrust zyada acceleration deta hai. Lekin gravity neeche kheenchti hai; atmosphere ka drag uski gati rokta hai. Rocket tabhi upar accelerate karta hai, jab uska upward thrust, gravity aur drag, in dono ke virodh se bada ho. To jawab hai: rocket hawa ko nahi dhakelta. Woh gas peeche fenkakar thrust banata hai, isiliye khaali antariksh mein bhi aage badh sakta hai; prakshepan ke dauran thrust ko gravity aur drag se jeetna hota hai.