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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 space-ship travelling in the interstellar medium is picking up...

A space-ship travelling in the interstellar medium is picking up dust& at a rate dMdt=\alphav\dfrac{dM}{dt} = \alphav, where α\alpha is a positive constant,& vv is the instantaneous velocity and& MM& is the total mass of the space-ship at any instant.& The instantaneous acceleration of the space-ship& is

Options

  1. A

    & \dfrac{− 2αv^{2}}{M}

  2. B

    & −\alphav2M\dfrac{- \alphav^{2}}{M}

  3. C

    & \dfrac{− αv^{2}}{2M}

  4. D

    −\alphav2− \alphav^{2}

Correct answer

B.

& −\alphav2M\dfrac{- \alphav^{2}}{M}

Step-by-step solution

dMdt=\alphav\dfrac{dM}{dt} = \alphav

Fthrust=−vdMdt=Ma{F}_{thrust} = - v\dfrac{dM}{dt} = Ma

⇒−v(\alphav)=Ma⇒ - v\left(\alphav\right) = Ma

⇒a=−\alphav2M⇒ a = - \dfrac{\alphav^{2}}{M}

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