Atoms, molecules, electrons, photons, protons etc.
We use the equation of motion for vertical component,

Here,
is displacement of bullet,
is vertical initial velocity of bullet which is equal to zero because bullet was fired horizontally, and t is time of flight.
Therefore,

Given, 
Substituting the values, we get time of flight

Answer:
Number of electrons, 
Explanation:
It is given that,
Charge, q = 4.33 C
We need to find the number of electrons that make 4.33 C of charge. According to quantization of charge as :

n = number of electrons
e = electron's charge



So, the number of electrons are
Hence, this is the required solution.
Answer:
84 kj/min = 1.4 kj/sec
Power Out / Power In = Heat Out / Heat In - Coefficient of Performance
1.4 kj/sec / 1.2 kj/sec = 1.17 = COP