Question

A ball is dropped downwards, after 1 sec another ball is dropped downwards from the same point. What is the distance between them after 3 sec?(a) 25 m (b) 20 m(c) 50 m (d) 9.8 m

Answer 1

Given:

A ball is dropped downwards, after 1 sec another ball is dropped downwards from the same point.

To find:

Distance between them after 3 seconds.

Calculation:

Time for which 1st ball travels is 3 sec.

Distance travelled by 1st ball be d1 :

$d1 = ut + \dfrac{1}{2} a {t}^{2}$

$= > d1 = 0 + \dfrac{1}{2} \times 10 \times {(3)}^{2}$

$= > d1 = \dfrac{1}{2} \times 10 \times9$

$= > d1 = 45 \: m$

Let distance travelled by 2nd ball be d2:

Time for which 2nd ball travels is 3-1 = 2 sec.

$d2 = ut + \dfrac{1}{2} a {t}^{2}$

$= > d2 = 0 + \dfrac{1}{2} \times 10 \times {(2)}^{2}$

$= > d2 = \dfrac{1}{2} \times 10 \times4$

$= > d2 = 20 \: m$

So , distance between the two balls will be:

$\Delta d = d1 - d2$

$= > \Delta d = 45 - 20$

$= > \Delta d = 25 \: m$

So final answer is :

$\boxed{ \sf{ \large{\Delta d = 25 \: m}}}$

Answer 2

your answer is option A)25 m ..

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