Answer:
The maximum electrical force is
.
Explanation:
Given that,
Speed of cyclotron = 1200 km/s
Initially the two protons are having kinetic energy given by

When they come to the closest distance the total kinetic energy is converts into potential energy given by
Using conservation of energy


Put the value into the formula


We need to calculate the maximum electrical force
Using formula of force



Hence, The maximum electrical force is
.
The answer is "friction and air resistance" gravity does some of the work by keeping the object from floating away, but friction and air resistance does the biggest part. Friction is how rough the ground it meaning on tile, dirt, grass, etc... that would slow down the object and air resistance is the gravity pushing on the object also making it stop.
Hope this helps!