Question

A body dropped from the top of a tower covers 5x
distance in the last second of its fall. The time of
fall is if x is the distance covered in first second of
its fall-
(1) 2 sec
(2) 4 sec.
(3) 3 sec.
(4) (50/7) sec

Please provide me solution with method.. I will surely follow you back when you provide me method.... ​

Answer 1

Answer:

I think 3 sec is the answer

Explanation:

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Answer 2

Given:

A body dropped from a tower covers $5x$ distance in the last second and $x$ distance in the first second of its fall.

To Find:

The time of fall.

Solution:

We know that the distance covered by an object in uniformly accelerated motion in the nth second of its journey is given by

$s_n=u+\frac{a}{2}(2n-1)$

where $u$ is the initial velocity of the object and $a$ is the acceleration of the object.

Here, the body is starting from rest, so the initial velocity of the object, $u=0$

   $s_1=x$

⇒ $\frac{a}{2} =x$

   $s_n=5x$

⇒ $\frac{a}{2} (2n-1)=5x$

⇒ $x(2n-1)=5x$

⇒ $n=3s$

Hence, the time of the fall is equal to 3 seconds.