[zafka]

In the ideal case, the math is pretty simple. The kinetic energy in 1/2MV^2 . (integral from 0 to mach 7) so if you know the weight of the missile...

[lifeisstillgood]

weapon that can fire a low-cost, 23-pound (10-kg) projectile at seven times the speed of sound

340m/s ~ speed of sound so thats 10kg at 2380 m/s (wow!)

523802380 Joules = 28322000 J

or 28MJ or 28MW if it needs a whole second of power or well the output of ~1/10 second of a mid sized nuclear power station

Yes it needs a lot of power

[ojii]

First sentence of the article: "The U.S. Navy is planning sea trials for a weapon that can fire a low-cost, 23-pound (10-kg) projectile"

[jwmerrill]

Just the difference between 0 and Mach 7, not the integral.