## BdPho regional Mymensingh Higher Secondary 2019/4

Discuss Physics and Physics Olympiad related problems here
samiul_samin
Posts: 1007
Joined: Sat Dec 09, 2017 1:32 pm

### BdPho regional Mymensingh Higher Secondary 2019/4

Lily is in a spaceship moving at speed $V=0.5c$ with respct to a viewer at rest on earth. Her friends james and severus are also in their own spaceships.Lily is watching that Severus is going forward at a speed $V_1=0.8c$ and James is going backward at a speed $V_2=0.85c$.
How fast is James going according to Severus?

samiul_samin
Posts: 1007
Joined: Sat Dec 09, 2017 1:32 pm

### Re: BdPho regional Mymensingh Higher Secondary 2019/4

$v_{JS}=\dfrac{0.85c+0.8c}{1+\dfrac {0.85c\times 0.8c}{c^2}}=0.98c$