Q34 / 208 · NTA Abhyas (NEET) 2020 · Physics · Gravitation

The time period of a satellite of earth is 5 h. If the separation between the earth and the satellite is increased to 4 times the previous value, the new time period will become 

  • Correct answer
    A
    40 h
  • B
    20 h
  • C
    10 h
  • D
    80 h

Solution

Using Kepler's IIIrd law

T 2 ∝ r 3

T ′ 2 T 2 = ( r ′ ) 3 r 3

⇒ T '2 T 2 = ( 4R ) 3 ( R ) 3

T '2 =64  T 2

⇒ T '2 =8T⇒T'=8×5=40  h

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

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