Question

a stone is dropped from certin height which can reach the ground in5s after 3s of its fall it is again allowed to fall then the time taken by stone to reach the ground for reamining distance is:​

Answer 1

Answer:

The question says that a ball is dropped from some height

Let the height = h meter

Time taken to hit the ground = 5 seconds

Using second equation of motion

=> s= ut + 1/2at²

So

h = 0*5 + 1/2*g*5²

= 5*5² = 125m (g=10 m/s²)

Now it is given that the ball is stopped after 3 seconds of its fall

Using second equation ( t= 3 seconds)

h' = 45 m ( you can calculate this yourself)

Therefore from 45 m position it is again dropped i.e u = 0

Height to travell now = 125 - 45 = 80 m

Again applying second equation of motion (h=80m)

80 = 0*t + 1/2g*t²

80 = 5 t²

Therefore t = 4 seconds

Now total time = 3 + 4 = 7 seconds (as the stone had already travelled for 3 seconds)

Explanation: