A balloon tied up with a wooden piece is moving upward with velocity of 15m/s. At a height of 300m above the ground, the wooden block detached from the balloon. How much time will it take to reach the ground?

Assume the wooden piece prevents the balloon from rising, is not so heavy as to cause the balloon to descend. and the 15 m/s is horizontal velocity “riding the wind,” That horizontal velocity does not affect the time the wood will take to reach the ground after release. Initial vertical velocity is zero.

s = u t + 1/2 g t^2

s is the height above ground, 300 m.

u is initial vertical velocity, zero.

t is time to reach the ground.

g is acceleration of gravity near Earth, 9.8 m/s^2.

300 m = 0 t + 1/2 (9.8 m/s^2) t^2

300 m = (4.9 m/s^2) t^2

61.22 s^2 = t^2

7.82 seconds = t