Acyclist rides 8.0 km east for 20 minutes, then he turns and heads west for 8 minutes and 3.2 km. finally he rides east for 16 km, which takes 40 minutes. (a) what is the final displacement of the cyclist? (b) what is his average velocity?

Displacement: 20,8 to the east.

Average velocity: 18,35 km/hour

Explanation:

In order to solve this you first have to calculate the total displacement that the cyclist rode, in this case we will use east as positive distance and west as negative:

+8 km -3,2 km +16 km= 20,8

Now the average velocity is the result of the displacement by the total time it took:

20,8*60/68= 18,35 km/hr

Now we know that the average belocity would be 18,35 kilometer per hour.

a and b sometimes have a positive value