Answer:
The time taken by the falling object is 2.04 sec
Solution:
The initial velocity
![V = -10 m/s](https://img.qammunity.org/2020/formulas/physics/middle-school/sj3wc7nc2l54oncedivnf2gq7rv6u0ksqk.png)
The final velocity
![V_1 = -30m/s](https://img.qammunity.org/2020/formulas/physics/middle-school/2wi3zycwgmlsjn9umotmr52v5rdhdng9e0.png)
Let us assume that the time taken is t sec
We know that the acceleration due to gravity
![g = 9.8m/sec^2](https://img.qammunity.org/2020/formulas/physics/middle-school/e0yggdw7k577cfohal2rrq5aq4p2cl39s9.png)
As per the free falling object motion,
![V_1 = V -gt](https://img.qammunity.org/2020/formulas/physics/middle-school/gv0u8rn94rlnxuiof4h9a2mshz5wclocil.png)
![-30 = -10 -9.8* t](https://img.qammunity.org/2020/formulas/physics/middle-school/juxllar368k4bhax93ujem8b3pvtc37e6n.png)
![-30+10 = -9.8* t](https://img.qammunity.org/2020/formulas/physics/middle-school/gyuv9nsz6ctrzj1nte30ztuul16umhrd1b.png)
![-20 = -9.8* t](https://img.qammunity.org/2020/formulas/physics/middle-school/k651n9h998wht84ffvf6mcryp74d5smals.png)
![t =(20)/(9.8) = 2.04](https://img.qammunity.org/2020/formulas/physics/middle-school/lgdes43kntjoejx5ttym11wiw1uj7kiyh9.png)
So, it takes total 2.04 sec