The rest energy of a particle is

where

is the rest mass of the particle and c is the speed of light.
The total energy of a relativistic particle is

where v is the speed of the particle.
We want the total energy of the particle to be twice its rest energy, so that

which means:


From which we find the ratio between the speed of the particle v and the speed of light c:

So, the particle should travel at 0.87c in order to have its total energy equal to twice its rest energy.
Шада и я тебя понимаю с чего начать с того ни другого человека дал в долг у меня в здоровье
If the distance is proportional to the square of the time, then the distance in 9 seconds will be (9/8)² as long as the distance in 8 seconds.
(9/8)² = 1.265625
(64 ft) · (1.265625) = <em>81 ft. </em>