ANSWER:
3408.81 kg
STEP-BY-STEP EXPLANATION:
Given:
v = 111 m/s
Ek = 21000000 J
We have that the formula for kinetic energy is as follows:
[tex]E_k=\frac{1}{2}\cdot m\cdot v^2[/tex]We substitute the values given in the exercise and solve for m (mass)
[tex]\begin{gathered} 21000000=\frac{1}{2}\cdot m\cdot111^2 \\ m=\frac{21000000\cdot2}{111^2} \\ m=3408.81\text{ kg} \end{gathered}[/tex]The mass of the helicopter is 3408.81 kilograms.