Answer:98.4 m
Step-by-step explanation:
Given
Descending velocity of balloon(v)=5 m/s
velocity of stone relative to balloon(u)=7 m/s
thus u is the horizontal velocity of stone and v vertical velocity of balloon
time travel by stone to reach ground=4 s
![h=ut+(at^2)/(2)](https://img.qammunity.org/2020/formulas/physics/college/mkygvn7pueyiql0ysom5on2w5eob9dpp9n.png)
where u=initial velocity
here u=5 m/s
t=4 s
a=g
![h=5* 4+(9.8* 4^2)/(2)=98.4 m](https://img.qammunity.org/2020/formulas/physics/college/jr8cak9fmgy72j23hy61k1gk6q17bzv8ff.png)
horizontal distance traveled in this time
![R=u* t](https://img.qammunity.org/2020/formulas/physics/college/15s0hcaj9il2vo7dti73x4o9jf43iqp1fm.png)
![R=7* 4=28 m](https://img.qammunity.org/2020/formulas/physics/college/njf8g7awgjaimrk18dkuk32k8ylvmbq0f2.png)
Thus stone at distance of 28 m from balloon
Also balloon and stone will be at same height at the time when rock hits ground