# Can two electron moving in opposite direction move faster than light? [duplicate]

Suppose we are moving two electrons in opposite direction both having a speed of 1.6e8 meter per sec.When they will cross each other then their relative velocity will be 3.2e8 ms_1.Isn't it faster than speed of light?

## marked as duplicate by rob♦Nov 21 '18 at 6:03

The problem is that although your frame of reference(the electron) is moving at speeds close to light, you are using GALILEAN TRANSFORMATION. You should use LORENTZ TRANSFORMATION to get the right relative speed.

Below is the Relativistic Velocity Transformation : $$u=\frac{\acute{u}+v}{1+\acute{u}v/c^2 }\$$ Where,

u=velocity of particle as measured from frame S

$$\acute{u}$$=velocity of particle as measured from frame $$\acute{S}$$

v=velocity of frame $$\acute{S}$$

• With common questions like this, it's better to search for an existing duplicate than to write a fresh answer. – PM 2Ring Nov 21 '18 at 5:38