A drone of mass changes its velocity in two successive stages while flying at…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A drone of mass 5.0kg changes its velocity in two successive stages while flying at constant altitude.
Stage 1: The drone is initially moving due east with a speed of 10ms−1. A steady wind acts for 4s, after which its speed is 10ms−1 directed 30∘ north of east.
Stage 2: Immediately thereafter, the drone’s rotors act for 3s, bringing its velocity to 12ms−1 due north.
(i) For the initial, intermediate and final velocities, write the momentum components along the east (x) and north (y) directions.
(ii) Calculate the change in momentum during Stage 1 and determine the average force exerted by the wind.
(iii) Calculate the change in momentum during Stage 2 and determine the average force exerted by the rotors.
(iv) Find the net change in momentum from the start of Stage 1 to the end of Stage 2, giving its magnitude and direction.