Question

A stone freely falls from the top of a building of height 180m. calculate the time for the stone reach the ground? method​

Answer 1

Answer :

Height of building = 180m

We have to find time taken by ball to reach the ground$.$

_________________________________

◈ For a body falling freely under the action of gravity, g is taken positive.

Initial velocity = zero

Let's apply 2nd eq. of kinematics :

➝ H = ut + (1/2)gt²

➝ 180 = 0 + (1/2)(10)t²

➝ t² = 36

➝ t = √36

➝ t = 6s

Answer 2

GiveN :

• Height = 180 m
• Initial velocity (u) = 0 m/s

To FinD :

• Time interval

SolutioN :

Use 2nd equation of Kinematics

ㅤㅤㅤㅤㅤㅤㅤㅤ

$\implies \sf{s\ =\ ut\ +\ \dfrac{1}{2} gt^2} \\ \\ \\ \\ \sf{Here} \begin{cases} \sf{s\ is\ height\ of\ building} \\ \\ \sf{u\ is\ initial\ velocity} \\ \\ \sf{g\ is\ acceleration\ due\ to\ gravity} \\ \\ \sf{t\ is\ time\ interval} \end{cases} \\ \\ \\ \\ \implies \sf{180\ =\ 0\ \times\ t\ +\ \dfrac{1}{2} \times\ 10\ \times\ t^2} \\ \\ \\ \\ \implies \sf{180\ =\ 0\ +\ 5t^2} \\ \\ \\ \\ \implies \sf{t^2\ =\ \dfrac{180}{5}} \\ \\ \\ \\ \implies \sf{t^2\ =\ 36} \\ \\ \\ \\ \implies \sf{t\ =\ \sqrt{36}} \\ \\ \\ \\ \implies {\underline{\boxed{\sf{t\ =\ 6\ s}}}}$