I think you mean PHYSICS, not physic. There's an amazing difference between the two.
http://www.answers.com/physic
http://www.answers.com/physics
How long (in ns) does it take light to travel 1.00 m in vacuum?
What distance does light travel in water during the time that it travels 1.00 m in vacuum?
2 answers
distance= speedlight*time
solve for time.
solve for time.