Question
      
        A stone is dropped from a rising balloon at a height of $$76\,m$$  above the ground and reaches the ground in $$6s.$$  What was the velocity of the balloon when the stone was dropped? Take $$g = 10\,m/{s^2}.$$      
       A.
        $$\left( {\frac{{52}}{3}} \right)\,m/s\,{\text{upward}}$$                 
              
       B.
        $$\left( {\frac{{52}}{3}} \right)\,m/s\,{\text{downward}}$$              
       C.
        $$3\,m/s$$              
       D.
        $$9.8\,m/s$$              
            
                Answer :  
        $$\left( {\frac{{52}}{3}} \right)\,m/s\,{\text{upward}}$$      
             Solution :
        $$\eqalign{
  & S = ut + \frac{1}{2}a{t^2}  \cr 
  &  - 76 = 4 \times 6 - \frac{1}{2} \times 10 \times {\left( 6 \right)^2} \Rightarrow u = \frac{{52}}{3}m/s \cr} $$