A man walks on a straight road from his home to a market 2.5 km away with a speed of 5 km h ^-1 . Finding the market closed, he instantly turns and walks back home with a speed of 7.5 km h^-1 . What is the magnitude of average velocity.

A man walks on a straight road from his home to a market 2.5 km away with a speed of 5 km h ^-1 . Finding the market closed, he instantly turns and walks back home with a speed of 7.5 km h^-1 . What is the average speed of the man over the interval of time (i) 0 to 30 min, (ii) 0 to 50 min, (Hi) 0 to 40. min? [Note: You will appreciate from this exercise why . it is better to define average speed as total path length divided by time, and not as magnitude of average velocity. You would not like to tell the tired man on his return home that his average speed was zero!]

A cyclist starts from the centre Oof a circular park of radius 1 km, reaches the edge Pof the park, then cycles along the circumference, and returns to the centre along QO as shown in Fig. 4.21. If the round trip takes 10 min, what is the (a) net displacement, (b) average velocity, and (c) average speed of the cyclist?