A balloon moving upwards with constant velocity 10m/s . if we release the stone from balloon , then, initial speed of stone = 10m/sec .

now,

initial speed = 10m/sec

time = 11sec

let H is the height of balloon when stone is dropped .

use kinematics equation ,

S = Ut + 1/2at²

-H = 10 × 11 - 1/2 × 10 × (11)²

= 110 - 5× 121

= 110 - 605

= -495 m

- H = -495 m

hence, H = 495 m

so, height of balloon is 495m when stone is dropped .