question_answer

A ball is thrown vertically downward with a velocity of 20 m/s from the top of a tower. It hits the ground after some time with a velocity of 80 m/s. The height of the tower is : \[\left( g=10\text{ }m/{{s}^{2}} \right)\] [NEET 2020]

A) 340 m

B) 320 m

C) 300 m

D) 360 m

Correct Answer: C

Solution :

[c]

\[{{v}^{2}}={{u}^{2}}+2gh\]

\[v=80\,m/s\]

\[u=80\,m/s\]

\[h=\frac{{{v}^{2}}-{{u}^{2}}}{2g}=\frac{6400-400}{20}=300\,\,m\]