Hi, I was given a question in which I had to work out the speed of an object given its momentum and its mass. Now I had to answer what would be the new speed if the momentum doubled. So, from what I understand, the rest mass can't change, it is like a constant for a given body. So, in other words, in this case, it is the velocity that is going to change. In order to find by what factor v must be increased in order to yield an increase in momentum of two I tried to rearrange the following equation: v/√1-(v2/c2 = 2 Is this what I should do? Can anyone please maybe give me a hint of what step I should take?