PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A delivery van starts from a warehouse O. It first travels 10km due east at 36kmh−1 and then 6km due north at 24kmh−1. The van must finally proceed directly to a delivery point D that is located 20km due east of O. Assume turning times are negligible and each stage is covered at constant speed.
(i) Determine the magnitude and direction of the displacement the van must cover during the third stage to reach D.
(ii) Calculate the time taken in each of the first two stages.
(iii) If the driver desires the magnitude of the average velocity for the complete trip to be exactly 40kmh−1, compute the minimum constant speed required during the third stage.
(iv) Using the value obtained in part (iii), evaluate the average speed for the whole trip and comment on its relation to the magnitude of the average velocity.