a body dropped from the top of a tower falls through 40 m during the last two seconds of its fall.

Asked by  | 23rd Jul, 2009, 02:30: PM

Expert Answer:

Let the h is the  height of cliff and stone takes n seconds to reach the ground.

The distance travelled by the particle in nth sec

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

Here, Snth = 40 m , u = 0 , a = 10 m/s2

so,    40 = 10 ( 2n - 1) / 2

or,           n = 4.5 sec

So, the stone takes 4.5 s to reach the ground from top of the tower.

Now, the height of the tower

h = ut + gt2 /2

    = 0 + 10 (4.5 )2 /2

    = 101.25 m

Answered by  | 23rd Jul, 2009, 08:23: PM

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