In the lab,charged particles are directed toward one another,each at speed 0.500 c.What is the speed of the particles moving toward the left with respect to the particles moving to the right?
A) 0.500 c
B) 0.00
C) 1.00 c
D) 0.800 c
E) 1.25 c

Question

Quizplus · Accepted Answer

When two particles are moving towards each other, we can use the relative velocity formula:
v = (v1 - v2) / (1 - v1v2/c^2)
where v is the velocity of one particle with respect to the other, v1 and v2 are the velocities of the particles and c is the speed of light. 
Plugging in v1 = v2 = 0.5c, we get:
v = (0.5c - (-0.5c)) / (1 - 0.5c(-0.5c)/c^2) 
v = 1c / (1 + 0.25) = 0.8c
Therefore, the particles moving towards the left are moving at 0.8c with respect to the particles moving towards the right. So the best choice is D).

In the Lab,charged Particles Are Directed Toward One Another,each at Speed