Question

a body is drop from the height of 122.5 m find the time taken by the body to reach the ground and the velocity of which it will hit the ground

Answer 1

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Answer 2

Given :

Height form which body is dropped , h = 122.5 m .

Initial velocity , u = 0 m/s .

To Find :

The time taken by the body to reach the ground and the velocity of which it will hit the ground .

Solution :

Let , final velocity be v .

By equation of motion :

$v^2=u^2+2ah$

Here , $a=g=9.8\ m/s^2$ ( Acceleration due to gravity )

Putting all given values , we get :

$v=\sqrt{2ah}\\\\v=\sqrt{2\times 9.8\times 122.5}\ m/s\\\\v=49\ m/s$

Now , time is given by equation :

$v=u+gt\\\\t=\dfrac{v-u}{g}\\\\t=\dfrac{49}{9.8}\ s\\\\t=5 \ s$

Therefore , time taken is 5 s and velocity with which it hit the ground is 49 m/s .