### crossing speed of light

We can't cross d speed of light! This is universal truth. Bt my question is if we somehow travel wid a speed "3/4 x c " in a train around d earth and at d same instant of time again we run at a speed "2/3 x c" inside it. . i.e. Speed of d train 3/4 c and speed of me 2/3 c (inside d train). Then our relative velocity will be " (3/4 + 2/3)xc " = " 1.42 x c" and its greater than speed of light . ? HOW???## Answers

Time slows so that c is always measured the same. In essence, you can never approach the speed of light because time dilates and space contracts so that c is always measured the same.

This is the beauty of relativity, and u had asked the best question physics had ever came across. But you what, when Einstein formed the equation of relativity he put forward sth out of the thought and to your question, he put another equation that says u+v/(1+ uv/c^2). This equation says no matter how fast u r traveling u cant surpass the light speed.

There are some points which have been arise in my mind about your question:

Firstly, from the results of special theory of relativity, when v>c then 1-(v^2/c^2) becomes negative, so its square root does not exists at all physically and in simple real-calculus.

Secondly, If we are considering the velocities approaching or greater than light, then relativistically, we have to follow the Velocity-Addition Rule (u+v)/(1+uv)

In your case, This leads us to the result 0.945 or even more to 2.835. So speed cannot be greater than speed of light.

Firstly, from the results of special theory of relativity, when v>c then 1-(v^2/c^2) becomes negative, so its square root does not exists at all physically and in simple real-calculus.

Secondly, If we are considering the velocities approaching or greater than light, then relativistically, we have to follow the Velocity-Addition Rule (u+v)/(1+uv)

In your case, This leads us to the result 0.945 or even more to 2.835. So speed cannot be greater than speed of light.

That's where Einstein comes.... then it leads to length contraction, n you will not be crossing speed of light.