A toy plane has a mass of 2.5 kg and is 18 m above the ground. It is moving at 4.5 m/s. How much mechanical energy does the toy plane have? 416 J 441 J 466 J 491 J

Mechanical energy is the sum of kinetic energy and potential energy, or E=Ek+Ep. So Ek = (1/2) * m*v² where m is the mass of the object and v is it's velocity. Mp=m*g*h where m is the mass, g=9.81 m/s² and h is the height of the object. So after we input the numbers the total mechanical energy is

E = (1/2) * 2.5 * (4.5²) + 2.5*9.81*18 = 25.3125 J + 441.45 J = 466.7625 J. The correct answer is E = 466 J.