starting from ypur 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,
t1=s1/v1=200/4=50 s,
t2=s2/v2 = 280/7 =40 s.
total time =50+40 =90 s.
Average velocity = 80/90=0.89 m/s.

Note!
Average speed=total distance travelled/ total time taken=(200+280)/90=5.33 m/s

To calculate the average velocity from your house to the post, you need to divide the total displacement by the total time taken.

First, let's find the total displacement. You ran 200m east and then 280m west. Since these displacements are in opposite directions, we can subtract them to find the net displacement:

Net displacement = 200m - 280m = -80m (negative sign indicates the direction is west)

Next, let's calculate the total time taken. We need to consider the time taken for running east and the time taken for running west separately.

Time taken for running east:
Distance = 200m
Speed = 4m/s
Time = Distance / Speed = 200m / 4m/s = 50s

Time taken for running west:
Distance = 280m
Speed = 7m/s
Time = Distance / Speed = 280m / 7m/s = 40s

Now, let's find the total time taken by adding the time taken for running east and the time taken for running west:

Total Time = Time taken for running east + Time taken for running west = 50s + 40s = 90s

Finally, we can calculate the average velocity:

Average Velocity = Total Displacement / Total Time = -80m / 90s = -0.89 m/s

Therefore, the average velocity from your house to the post is approximately -0.89 m/s (westward direction).