Science, asked by AFridiiiKhaaannn, 1 year ago

A body is allowed to fall from a height of 20m from the ground ,How much time will it take to reach the ground?

Answers

Answered by PrithishS

This problem can solved by the formula v²-u²=2as (final velocity squared - initial velocity squared = 2 times acceleration times distance) and a=v-u/t (acceleration = final velocity - initial velocity by time). [lets assume acceleration due to gravity = 10m/s²]

v²-u²= 2as
v²-0 = 2x10x20
v² = 400
v = 20

a = v-u/t
10 = 20-0/t
t = 20/10
= 2 second

Hope this helps...

AFridiiiKhaaannn: but answer is t = 1 sec . How ?

AFridiiiKhaaannn: I got it , v= u + at in 2nd para step , and taking u = 0 and v =20 we get 20/a i.e. 10 and 20/10 is t=2 sec

PrithishS: small typing error in 2ng para.

PrithishS: instead 20 i typed 10

AFridiiiKhaaannn: if you type 20 instead of 10 then it will end up being 1 sec =t but answer is 2 sec

AFridiiiKhaaannn: ur answer is correct

Answered by abhi178

a body falls from height of 20m .
we know,
for free fall body initial velocity (u) = 0

we use the formula,
S = ut + 1/2at²
here, S is height of body
u is the initial velocity of body
and a is Acceleration.

here, u = 0 , S = 20 and a = 10 m/s² { acceleration due to gravity }

now, 20 = 0 + 1/2 × 10t²
40 = 10t² => t ² = 4
so, t = 2 sec

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