A stone is dropped from a height of 125 m. If the
wstone is acted upon by a uniform" acceleration 10ml
calculate, when and with what velocity it will strike
the ground.
Answers
Given :
➳ Height of building = 125m
➳ Acc. due to gravity = 10m/s²
To Find :
➝ Time taken by stone to reach at ground.
➝ Final velocity at which stone touched the ground.
SoluTion :
Here, acceleration due to gravity continuously acts in downward direction. We can apply equation of kinematics to solve this question.
For a body, falling freely under the action of gravity, g is taken positive.
◈ Time of journey :
\dashrightarrow\rm\:H=ut+\dfrac{1}{2}gt^2
\dashrightarrow\rm\:125=0+\dfrac{1}{2}\times 10\times t^2
\dashrightarrow\rm\:t^2=25
\dashrightarrow\underline{\boxed{\bf{\red{t=5s}}}}\:\gray{\bigstar}
◈ Final velocity :
\dashrightarrow\rm\:v^2-u^2=2gH
\dashrightarrow\rm\:v=\sqrt{2gH}
\dashrightarrow\rm\:v=\sqrt{2\times 10\times 125}
\dashrightarrow\rm\:v=\sqrt{2500}
\dashrightarrow\underline{\boxed{\bf{\blue{v=50\:ms^{-1}}}}}\:\orange{\bigstar}