# Superman needs Physics Power!

**Classical Mechanics**Level 3

**Universal Projection Pad**, this gadget simply adjusts to the environment and calculates the minimum projection velocity required for Superman to go back to Earth from a particular planet. Superman contemplated and wanted to find out the time taken to do so, find that time taken and save the world. Round your answer to \(2s.f.\) in seconds and in standard form.

*Present from Issac Newton*; Physicists can be heroes too

**Details**:

Assume that the journey is vacuum, which is of course, space and that the velocity projected does not change during the journey as no external forces are included.

Assume that \(G\), gravitational constant is \(6.67\times 10^{ -11 }{ m }^{ 3 }{ kg }^{ -1 }{ s }^{ -2 }\)

Radius of the Moon: \(1.7\times 10^{ 6 }{ m }\)

Mass of the moon: \(7.35\times 10^{ 22 }kg\)

The journey is about \(384,400km\)