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NTA Abhyas 2020

Exam: NTA Abhyas
Year: 2020
Subject: Physics
Chapter: Center of Mass, Momentum and Collision

NTA Abhyas 2020 · Physics · Center of Mass, Momentum and Collision

A shell in air explodes into n equal fragments, k of the fragments...

A shell in air explodes into

n

equal fragments,

k

of the fragments reach the ground earlier than the other fragments. The acceleration of their centre of mass subsequently will be

Options

A $g$
B $\left(n - k\right)g$
C\dfrac{ $\left(n - k\right)g}{k}$
D $\left(n - k\right)ng$

Correct answer

D. $\left(n - k\right)ng$

Step-by-step solution

{a}_{cm} = \dfrac{Σ{m}_{i}{a}_{i}}{Σ{m}_{i}}

<br /><br />Till all the particle remains in air center of mass remains stationary. When k particles hit the ground then center of mass shifts with accelaration :<br /><br />

{a}_{cm} =\dfrac{\left(n - k\right)}{n}g

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