Motion In A Straight Line Ques 31
31. 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 : $(g=10 m / s^{2}) \quad$
[2020]
(a) $340 $ $m$
(b) $320$ $ m$
(c) $300$ $ m$
(d) $360$ $ m$
Show Answer
Answer:
Correct Answer: 31.(c)
Solution:
- (c)
Using $v^{2}=u^{2}+2 g h$
Height, $h=\frac{v^{2}-u^{2}}{2 g}=\frac{(80)^{2}-(20)^{2}}{2 \times 10}$
$ =\frac{6400-400}{20}=300 $ $m $
BETA
