posted by carak .
starting from your house, run 2oom east at an average speed of 4m/s, then turn around and run 280m west at an average spped of 7m/s to a post.
1) calculate Average velocity from house to post
Average velocity=final displacement/total time taken
Final displacement = 280-200 = 80 m,
t2=s2/v2 = 280/7 =40 s.
total time =50+40 =90 s.
Average velocity = 80/90=0.89 m/s.
Average speed=total distance travelled/ total time taken=(200+280)/90=5.33 m/s