Question

if light has no mass then why does it affect by the gravitational pull of blackholl?

Answer 1

According to Newton
e=mc^2
energy=mass*speed of light
so light being a energy it should have mass
I have read that light exerts pressure on the object on which it is striking,
When a light is trapped inside a botte (just imagine) the light will constitute to mass of the bottle.

I hope this will help

Answer 2

Accordinv to newton theory gravity attracts only that object which have mass.But mass of light is negligible.It is pull towards the black hole due to the curved space.It takes shortest path to move and seems that attracting towards black hole.