Question

A ball is thrown vertically upwards from the top of a tower at 4.9 m/s. It strikes the pond near the base of the tower after 3 seconds. The height of the tower is

• A. 73.5 m
• B. 44.1 m
• C. 29.4 m
• D. None of these

Answer 1

Answer: (C)

. 29.4 m

GIven,

Initial velocity, u = - 4.9 m/s

Time taken = t = 3 s

Let us assume the downward direction as positive direction, then

Acceleration due to gravity = $g=9.8m/s^2$

Using the second equation of motion.

$h=ut+\frac{1}{2}g{t}^2,$
$\Rightarrow h=-4.9\times 3+\frac{1}{2}\times 9.8\times (3{)}^2$
$\Rightarrow h=-4.9\times 3+4.9\times 9=29.4m$

Thus the height of the tower is 29.4 m.