In a proton linear accelerator, a 8.6 ma proton current hits a target.
a. how many protons hit the target each second?
b. what is the energy delivered to the target each second if the protons each have a kinetic energy of 20 mev and come to a complete stop in the target? j/s

Wow.  In order to answer this, you need to go look up a couple definitions.
Relax.  Keep your seat.  Don't trouble yourself.  I'll go look them up for you.
It's a small price to pay to earn the whopping 5 points that awaits me at the
end of the rainbow.

1 Coulomb = 6.2415 x 10¹⁸ elementary charges
1 electron volt = 1.60217657 × 10⁻¹⁹ joules

Each proton carries one elementary charge, just like an electron does.

8.6 mA = 0.0086 Ampere =
               0.0086 coulomb per second = 5.3677 x 10¹⁶ charges per second

Energy delivered to the target =

           (number of protons) x (energy of each proton) =

(5.3677 x 10¹⁶)x(20 MeV) x (1,000 eV / MeV)x(1.60217657 × 10⁻¹⁹ joules / eV) =

         172 joules per second

         (172 watts)

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