Question

51.
A stone falls freely from rest. The distance covered in
last second is equal to distance covered in first 5 sec.
Total time of fall is :
(a) 5 sec
(b) 8 sec
(c) 13 sec
(d) 20 sec​

Answer 1

Answer:

Given u=0.

Distance covered in first 5 sec

= ut + 1/2 * g * t^2

= 1/2 * 10 * 5*5

=125 m.

According to question,

Distance travelled in last second = Distance travel in first 5 sec.

Snth = u + a/2* (2n - 1) =125m

10/2* (2n - 1) =125

2n - 1 = 25

2n = 26

n = 26/2

=13 sec.

Means total time = 13 sec.

Hope it's helpful to u.