Question

A rocket is headed away from earth at a speed of 0.8c. the rocket fires a missile at a speed of 0.7c (the missile is aimed away from earth and leaves the rocket at 0.7c relative to the rocket). how fast is the missile moving relative to earth? select one:
a. 1.5c

b. a little less than 1.5c

c. a little over c

d. a little under c

e. 0.75c

Answer 1

To solve this problem, let us consider that the Earth is the origin, the initial reference point. Therefore the speed of rocket plus the missile would be 0.8 C

Now after the rocket had moved away from Earth, it fired a missile at a speed of 0.7 C. Now the reference made to this is relative to the rocket. We have established that our initial reference point is the Earth, therefore the real speed of the missile with reference to Earth is:

Speed of missile relative to Earth = 0.8 C + 0.7 C

Speed of missile relative to Earth = 1.5 C

 

Answer is:

A