A drone lifts off from point O, flies 60m due east and 80m due north to reach point A in 10s. It then hovers at A for 5s and finally returns straight to a point B that lies exactly halfway between O and A along the line OA in another 5s.
(i) Find the straight-line distance OA.
(ii) Determine the magnitude and direction of the drone’s average velocity for the first 10s.
(iii) Calculate the drone’s total displacement OB at the end of the entire 20s described above.
(iv) Using the result of part (iii), find the magnitude and direction of the drone’s average velocity for the whole 20s period.
(v) Comment on how the value obtained in part (iv) compares with the average velocity for only the first 10s and explain the physical reason for the difference.