Apedestrian left his house and started walking on a straight street, resting at times as necessary. the graph below shows the distance he covered as a function of time. find the formula describing how his speed depends on the time, and graph this function.

From t= 0 to t=2, distance is a straight line, and hence speed is slope of that line.

Hence for 0<=t<2, speed =

From 2<=t<=2.5, distance remained constant at 8km, hence speed is 0 km/h.

From 2.5<=t<3, distance again a straight lines.

And hence speed = slope of line joining (2.5,8) and (3,10)

                              =

From 3<=t<4, distance remained constant at 10km. That means he is at rest.

Hence speed = 0 km/h for 3<=t<=4.

From 4<=t<5, distance again is a straight line.

Hence speed = slope of line joining (4,10) and (5,12)

                       =

Please refer the graph for speed.