An internet shopping company is planning to use drones to deliver packages.During a test the drone is hovering at a constant height above the ground.The mass of the drone is 5·50 kg. The mass of the package is 1·25 kg. See questions below
a) Determine the upward force produced by the droneWe can simplify the problem by drawing a free body diagram. This allows us to analyse the forces involved. We are told the drone is stationary, meaning the upwards and downwards forces are balanced. Therefore upwards thrust balances the weight of the drone and package. We can calculate the weight by using equation w = mg in datasheetW = mg = (5.5+1.25) * 9.8 = 66 Newtons. This must equal the upward force hence thrust = 66Nb) The package is now lowered using a motor and a cable. A battery supplies 12V across the motor. The resistance of the motor is 9∙6 Ω. Calculate the power dissipated by the motor. List knowns and unknown and apply to datasheet. We know the voltage and resistance, and there is an equation P = V2/R. Therefore:P = 122 / 9.6 = 15 Watts.c) While the package is being lowered the cable breaks. The upward force produced by the drone remains constant. Describe the vertical motion of the drone immediately after the cable breaks.The upwards force remains unchanged, however the weight of the system has decreased. Therefore there is an unbalanced force upwards, so the drone will accelerate upwards.
