Question

With respect to the earth, object 1 is moving at speed 0.80 c to the right. Object 2 is moving in the same direction at speed 0.80 c with respect to object 1. How fast is object 2 moving with respect to the earth?

Answer 1

0.976 c

Step-by-step explanation:

`v_(1e)` = velocity of object 1 relative to earth = 0.80 c

`v_(21)` = velocity of object 2 relative to object 1 = 0.80 c

`v_(2e)` = velocity of object 2 relative to earth

Velocity of object 2 relative to earth is given as

`v_(2e)= (v_(1e) + v_(21))/(1 + (v_(1e)v_(21))/(c^(2)))`

`v_(2e)= (0.80 c + 0.80 c)/(1 + ((0.80c)(0.80c))/(c^(2)))`

`v_(2e)` = 0.976 c