Question

21.
A body falls freely from a height of 125 m (g = 10 m/s). After 2 sec gravity ceases to act
Find time taken by it to reach the ground?​

Answer 1

Answer:

5.25 seconds

Explanation:

As body falls freely so its initial velocity will be zero.

now by using the equation s = ut + 1/2 at^2

we get the displacement cover by body in 2 second = 20 m

so distance left = 125 - 20 = 105 m

Now, by using the equation, v = u + at

we get the value final velocity in 2 seconds = 20 m/s

As after 2 seconds gravity ceases to act so its acceleration becomes zero.

So time taken by body to reach the ground = 105 / 20 = 5.25 seconds

Answer 2

Answer:

2.5 seconds

Explanation:

you just have to calculate the final velocity for the first two seconds and then take it as the initial velocity for the rest of the time