# Question 1.Two rockets of rest length L0 are approaching the earth from opposite directions at velocities ±0.6c. How fast (velocity) does one of them appear to the other? 1.2 c C 0.9c 0.8c 2. For 7.6% accuracy, What does an electron have this kinetic energy in MeV needed to be treated relativistically? Hint: The rest mass energy of an electron is 0.511 MeV. Express your answer in exponential form (example: scientific notation using E-7 for 10-7) to three significant figures and in the unit of MeV. Do not enter the unit 1.Two rockets of rest length L0 are approaching the earth from opposite directions at velocities ±0.6c. How fast (velocity) does one of them appear to the other?

1.2 c

C

0.9c

0.8c

2.

For 7.6% accuracy, What does an electron have this kinetic energy in MeV needed to be treated relativistically? Hint: The rest mass energy of an electron is 0.511 MeV.

Express your answer in exponential form (example: scientific notation using E-7 for 10-7) to three significant figures and in the unit of MeV. Do not enter the unit

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