Use KE= 1/2mv^2
So...
50,000=(.5)(1,000)v^2
50,000=500 x v^2
Divide 500 on both sides
100 = v^2
Square root both sides to get rid of v^2
Therefore v = 10 m/s
The shadow would subsequently drop the temperature in the city, forcing warmer air to rush in and violently destroy countless buildings. There would also be “black rain,” which would be the radioactive ash and dust that would liquify and pour down on the city and we would all die.