Question

a rocket with a mass of 400 lb travels at 27000 ft per sec. what is its kinetic energy in ft-lbf?

Answer 1

The kinetic energy:

$$K=0.5mv^2$$ $$m=400\ lb_m=\frac{400}{32.174}slugs$$

$$K=0.5\frac{400}{32.174}(27000)^2=4.5\cdot 10^9\ ft \cdot lb_f$$