Question -
Answer -
Mass of each star, M = 2 ×1030 kg
Radius of each star, R = 104 km = 107 m
Distance between the stars, r =109 km = 1012m
For negligible speeds, v =0 total energy of two stars separated at distance r
Now, consider the casewhen the stars are about to collide:
Velocity of the stars = v
Distance between the centers of the stars =2R
Totalkinetic energy of both stars 
Total potential energy of both stars 
Total energy of the two stars = 
Using the law ofconservation of energy, we can write:
