Get Answers to all your Questions

header-bg qa

The energy required to take a satellite to a height 'h' above Earth surface (radius of the Earth = 6.4 X 103km) is E1 and kinetic energy required for satellite to be in a circular orbit at this height is E2. The value of h for which E1 and E2 are equal, is:

 

  • Option 1)

    1.6 X 103km

  • Option 2)

    6.4 X 103km

  • Option 3)

    1.28 X 104km

  • Option 4)

     

    3.2 X 103km

Answers (1)

best_answer

 

Energy of satellite -

K=\frac{1}{2}mV^{2}=\frac{GMm}{2r}

U=-\frac{GMm}{r}

K\rightarrow Kinetic\: energy

U\rightarrow Potential\: energy

M\rightarrow mass\: of\: planet

m\rightarrow mass\: of\: satellite

E=K+U

E=-\frac{GMm}{2r}

E=Total\: energy

 

- wherein

K=-E

U=2E

U=-2K

V_{Surfuse}+E_{1}=U_{h}

\frac{-GM_{e}m}{R_{e}}+E_{1}=\frac{-GM_{e}m}{R_{e}+h}

E_{1}=GM_{e}m (\frac{1}{R_{e}}-\frac{1}{R_{e}+h})

E_{1}=\frac{GM_{e}m}{R_{e}+h}.\frac{h}{R_{e}}

Gravitational force 

F=ma_{c}=\frac{mv^{2}}{R_{e}+h}

E_{2}\Rightarrow \frac{mv^{2}}{R_{e}+h}=\frac{GM_{e}m}{(R_{e}+h)^{2}}

mv^{2}=\frac{GM_{e}m}{R_{e}+h}

E_{2}=\frac{mv^{2}}{2}=\frac{GM_{e}m}{2(R_{e}+h)}

E_{1}=E_{2}

\therefore \frac{h}{R_{e}}=\frac{1}{2}\Rightarrow h=\frac{R_{e}}{2}

=3200\: km

 

 


Option 1)

1.6 X 103km

Option 2)

6.4 X 103km

Option 3)

1.28 X 104km

Option 4)

 

3.2 X 103km

Posted by

admin

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE