Understanding Mechanical Energy of a National Geographic Drone
a. What is the mechanical energy of the drone at the surface?
b. What is the mechanical energy of the drone at the 150 m height?
c. Is the mechanical energy of the drone conserved, increased, or decreased? Explain your choice.
d. What is the work done by each force acting on the drone?
a. 0
b. 1.103625 MJ
c. Conserved
d. 1.103625/n MJ where n = The number of forces
Explanation:
A 750 kg National Geographic Drone is rising vertically up into the atmosphere at constant speed. The lift force pushing it upward is 125% of its weight. The drone reaches the cruising speed almost immediately. It takes 25 seconds for the drone to reach a height of 250m starting from the surface.
a. What is the mechanical energy of the drone at the surface?
The mechanical energy = The kinetic energy + Potential energy. Therefore, at the surface where the drone was initially at rest, the mechanical energy is 0.
b. What is the mechanical energy of the drone at the 150 m height?
The mechanical energy at a height of 150 m can be calculated by determining the potential energy gained, which is ME₁₅₀ = m·g·h. Plugging in the values, we get ME₁₅₀ = 750 kg × 9.81 m/s² × 150 m = 1103625 J = 1.103625 MJ.
c. Is the mechanical energy of the drone conserved, increased, or decreased? Explain your choice.
The mechanical energy of the drone is conserved as it is equivalent to the potential energy of the drone at the 150 m height.
d. What is the work done by each force acting on the drone?
The work done by each force is equal to the energy gained. Therefore, for n number of forces, the work done by each force is 1.103625/n MJ.