Question

A stone is projected up with a velocity of $4.9m/s$ from the top of a tower and it reaches the ground after 3 s. Then the height of that tower is

• A. 4.9 m
• B. 19.6 m
• C. 9.8 m
• D. 29.4 m

Answer 1

The correct option is D 29.4 m

From second equation of motion, $s=ut+a{t}^2/2$

Assume upward direction to be positive.

$u=4.9m/s,t=3sec,a=-9.8m/s^2$

$s=4.9\times 3-9.8\times 3^2/2$

$s=-29.4m$

Height = 29.4 m