JEE MainPhysicsGravitation
Two satellites A and B are revolving around the Earth in circular orbits. The ratio of their masses is m_A : m_B = 1 : 2 . If their orbital angular momenta are equal, the ratio of their kinetic energies K_A : K_B is
Options
- A1 : 4
- B1 : 8
- C8 : 1
- D1 : 2
Correct answer
B. 1 : 8
Step-by-step solution
The orbital angular momentum of a satellite is given by L = mvr . Using the orbital speed v = GM r , we can write L = m GMr . Given that L_A = L_B , we have: m_A r_A = m_B r_B r_A r_B = m_B m_A = 2 1 r_A r_B = 4 The kinetic energy of a satellite is K = GMm 2r . The ratio of their kinetic energies is: K_A K_B = ( m_A m_B ) ( r_B r_A ) K_A K_B = ( 1 2 ) ( 1 4 ) = 1 8 Thus, the ratio K_A : K_B is 1 : 8 . Answer: 1 : 8