Answer:
C = 0.0125 m/s⁴. The calculation procedure can be found in the attachment below. The concept of motion along a straight line with constant acceleration has been applied to solve the problem.
Explanation:
The sign convention chosen in this problem solution is upwards as positive and downwards negative. The equation of motion v = u + at has been used to calculate the constant C as only one unknown is contained in this equation. This is so because we have been given the initial velocity, the acceleration and the time taken. To solve future problems of this kind, first thing to check for is an equation of motion with the least number of unknown. This helps to reduce the complexity of the problem solution.
The answer is A. Trust me!
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 
1) use energy from food
2) get rid of wastes
3) maintain