Q20 / 208 · NTA Abhyas (NEET) 2020 · Physics · Gravitation

A particle is projected with velocity kve in the vertically upward direction from the ground into space (ve is escape velocity and k<1). The maximum height from the centre of the earth to which it can reach is

  • A
    Rk2+1
  • B
    k2R1-k2
  • Correct answer
    C
    R1-k2
  • D
    k2Rk2+1

Solution

Total energy of surface = Total energy at h height

⇒12mkve2+-GMmR=0+-GMmR+h

⇒k212mve2+-GMmR=-GMmR+h

⇒k212m2GMR-GMmR=-GMmR+h

⇒1R-k2R=1R+h

⇒1-k2R=1R+h

⇒R+h=R1-k2

Hence, the correct answer is option: 'C'.

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