An electric drone carries a surveying instrument. The instrument is held in a box with a large flat front facing the direction of travel.
Explain why this shape of box reduces the efficiency of the drone while it is moving forwards.
During a short forward flight, the battery transfers 1200 J of energy.
Of this energy, 300 J is dissipated to the thermal stores of the drone and the surroundings. The rest is transferred usefully by the propellers.
Calculate the efficiency of the drone during this flight.
The instrument box is replaced by a streamlined cover. During a later flight, the battery transfers 1500 J of energy and the efficiency of the drone is 0.84.
Calculate the energy dissipated during this flight.