Answer:
Explanation:
From the question we are told that
Nucleus diameter 
a 12C nucleus
Required kinetic energy 
Generally initial speed of proton must be determined,applying the law of conservation of energy we have
where
=initial kinetic energy
=final kinetic energy
=initial electric potential
=final electric potential
mathematically
where
=distance b/w charges
=nucleus charge 
=constant
=proton charge
Generally kinetic energy is know as
Therefore
Generally equation for radius is 
Mathematically solving for radius of nucleus
Generally we can easily solving mathematically substitute into v_1
Therefore the proton must be fired out with a speed of
Increasing the temperature causes the particles in the reaction to become kinetically excited, hitting one another in increasing frequency. Increased collision among means faster rate or reaction.
The part that causes the disc caliper piston to retract when the brakes are released is the square-cut O-ring.
The square cut seal is the most important part of a disc brake caliper, for keeping the brake behind the piston so that when you step on the brake pedal, it releases a pressure that applied to the piston which in return applies the pad to the rotor.
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