With respect to the earth, object 1 is moving at speed 0.90 c to the right. Object 2 is moving in the same direction at speed 0.70 c with respect to object 1. How fast is object 2 moving with respect to the earth?
A)0.64 c
B)1.6 c
C)0.16 c
D)0.80 c
E)0.98 c

Question

Quizplus · Accepted Answer

Using the relativistic velocity addition formula: v = (v1 + v2) / (1 + v1*v2/c^2), where v1 = 0.90c and v2 = 0.70c, the speed of object 2 with respect to the earth is 0.98c.

With Respect to the Earth, Object 1 Is Moving at Speed