Question

A ball thrown vertically upwards with a speed of $19.6\frac{m}{s}$ from the top of a tower returns to the earth in 6 s. Find the height of the tower:

• A. $60.6m$
• B. $56.6m$
• C. $58.8m$
• D. $Noneofthese$

Answer 1

The correct option is C

$58.8m$

$s=ut+\frac{1}{2}a{t}^2$

Let the height of the tower be $h$.

Here,

$u=19.6m/s$

$t=6s$

Height of the tower = h

$a=-g=-9.8m/s^2$ (It is taken as negative because the direction of acceleration due to gravity is downwards, while the initial velocity is upwards).

$\therefore h=(19.6\times 6)-\frac{9.8\times 6\times 6}{2}$

$=-58.8m$

Thus, the height of the tower is 58.8 m.