Question

A balloon is at a height of 81 m is ascending upwards with a velocity of 12m/s .a body of 2kg weight is dropped from it. if g=10 m/s , the body will reach the earth in how much time?

Answer 1

For balloon h(s)=81 m
u=0 m/s  v= 12 m/s
for a body  a=10 m/s²  u= -12 m/s
h or distance(s)=81 m

s=ut+1/2at²
81=-12t +5t²
5t²-12t-81=0
5t²+15t-27t-81=0
5t(t+3)-27(t+3)=0
(5t-27)(t+3)=0

t=27/5=5.2 second  is answer.