A cosmic ray (an electron or nucleus moving at speeds close to the speed of light) travels across the Milky Way at a speed of 0.98 times the speed of light. If the Milky Way is 30,000 pc across, how long does this journey take in our (essentially stationary) frame of reference and the cosmic ray's frame of reference, in years?

i think the answer is a, hope this is right, that would be my best guess.

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j