3. Two rockets approach Earth from opposite directions at a high speed v. What is the speed of a rocket as measured by the observer on the other rocket? (A) (B) 2v (C)(D) (E)

7. Which of the following statements about superconductivity is correct? (A) All materials become superconducting below 30 K (B) The resistance of a superconductor is zero (C) Superconductivity violates the first law of thermodynamics (D) Superconductivity violates the second law of thermodynamics (E) All the above are incorrect

3. Two rockets approach Earth from opposite directions at a high speed v. What is the speed of a rocket as measured by the observer on the other rocket?
(A)
(B) 2v
(C)
(D)
(E)

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