Kinetic energy (KE) is given by the formula:
\[ KE = \frac{1}{2}mv^2 \]
where \( m \) is the mass and \( v \) is the velocity.
If the hawk doubles its speed, then its new kinetic energy will be:
\[ KE_{\text{new}} = \frac{1}{2}m(2v)^2 = \frac{1}{2}m(4v^2) = 4 \left( \frac{1}{2}mv^2 \right) = 4 \times KE_{\text{initial}} \]
Given that the initial kinetic energy is 5.1 Joules:
\[ KE_{\text{new}} = 4 \times 5.1 , \text{J} = 20.4 , \text{J} \]
So, the best prediction for the hawk's kinetic energy at the end of the chase is:
20.4 J