Answer:
The bird is flying at a velocity of [tex]v=2\frac{m}{s}[/tex]
Explanation:
You should use the equation for the kinetic energy, that is:
[tex]K_{E}=\frac{1}{2}mv^{2}[/tex]
where [tex]K_{E}[/tex] is the kinetic energy, m is the mass of the bird and v is its velocity.
Solving for v:
[tex]mv^{2}=2K_{E}[/tex]
[tex]v^{2}=\frac{2K_{E}}{m}[/tex]
[tex]v=\sqrt{\frac{2K_{E}}{m}}[/tex]
And replacing the values given in the problem you have:
[tex]v=\sqrt{\frac{2*8J}{4kg}}[/tex]
[tex]v=\sqrt{\frac{16J}{4kg}}[/tex]
[tex]v=\sqrt{4\frac{m^{2}}{s^{2}}}[/tex]
[tex]v=2\frac{m}{s}[/tex]
