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.
Answer:
Explanation:
The answer is C. Both options are correct
Answer:
Speed=1.6km/hr. I'm not sure about b
Answer:
25%
Explanation:
use F=mg
then use the answer you get from that and plug it into W=Fxh
take that answer and divide it by 400 J and multiply by 100
round to sig figs
Time = 15/-0.5 = 14.5/-0.5 = 14.5s
The answer is 14.5s
Sorry no one would answer it sooner.