Question

A stone is released from rest from the top of a building of height 180 m. How much time elapses between the instant of release and the instant of impact with the ground?

Answer 1

Given:

The height of the building, h=180 m

The initial velocity of the stone, u=0 m/s

To find:

The time it takes for the stone to reach the ground.

Step-by-step explanation:

From the equation of motion,

`h=ut+(1)/(2)gt^2`

Where t is the time it takes for the stone to reach the ground and g is the acceleration due to gravity.

On substituting the known values,

`\begin{gathered} 180=0+(1)/(2)*10* t^2 \\ t=\sqrt{(180*2)/(10)} \\ =6\text{ s} \end{gathered}`

Final answer:

The time it takes for the stone to reach the ground is 6 s.