Question

A stone falls freely for 3 seconds and then earth ceases to attract it
How far will it fall in the next 3 seconds?
(A) 75m
(B) 110m

(C) 88.2
(D) 200m
​

Answer 1

Toyal time for journey =6s

During first 3 seconds of motion Body developed velocity due to Acceleration due to gravity

After 3 sec As given in the question earth cease(Stops) to attract it hence effect of gravity becomes 0

And body moves without any acceleration or with constant velocity

• For first 3 sec

1. Initial velocity =0 m/s
2. Acceleration due to gravity is 10m/s
3. Time =3seconds

Using 1st equation of motion

$v=u+at$

$v=0+10(3)=30ms^{-}$

Hence velocity after 3 sec of motion is 30m/s

After 3sec as given earth cease to attract it hence no acceleration act on body

Henec

We can use

$\huge{Speed=\frac{Distance}{Time}}$

$\green{ Distance }=Speed×time=30×3=\green{90m}$

Here 90 is taken as approximation

As value of acceleration due to gravity is Actually 9.8m/s For ezact answer use this value instead of 10m/s^2 As

we use value of gravity as 10 for simplicity

If we use g=9.8 then

Answer =88.2m/s^2