Show how to convert a mass in kg into MeV/c2 using E = mc2

What is the speed vfinal of the electron when it is 10.0 cm from charge 1?

Calculate the numbers of photons having a wavelength of 10.0 mm required to produce 1.0 kj of energycalculate the numbers of photons having a wavelength of 10.0 mm required to produce 1.0 kj of energy

Abox is sliding on a frictionless surface when it suddenly begins to rain heavily. if the downpour of rainfall falls vertically into the box