Hi Sun;
A joule is kgm^{2}/s^{2}.
As Robert explained, the equation is...
kinetic energy=(1/2)mv^{2}
16 kgm^{2}/s^{2}=(1/2)(2 kg)(x m/s)^{2}
The result we want is m/s.
The unit of kg is in the numerator of both sides of the equation. These cancel...
16 kgm^{2}/s^{2}=(1/2)(2 kg)(x m/s)^{2}
16 m^{2}/s^{2}=(1/2)(2)(x m/s)^{2}
16 m^{2}/s^{2}=(x m/s)^{2}
Let's take the squareroot of both sides...
4 m/s=x m/s
12/17/2013

Vivian L.