Question

Martin walked away from his school at a constant velocity for the first 30 seconds. He realized that he had to pick up a book from his friend's house which he had already passed. He turned around and walked to his friend's house at a constant velocity for 10 seconds. He stopped at his friend's house for 40 seconds and then walked away from school again at a constant velocity for the next 20 seconds. Which of the following graphs best represents Martin's motion?

Answer 1

Answer: The below graph shows Martin's motion.  

Step-by-step explanation:

let x represents the time(in seconds) and y represents the displacement in x seconds.

According to the question,

At first he walked away from the school for 30 second .

Thus, we will get a line having positive slope.

After that, he turned around and walked to his friend for 20 second.

Thus, we will get  a line having negative slope.

Now he wait 40 second in his friend's house.

Thus, after that we get a line that is parallel to x-axis.

Now, He again goes towards his school for 20 seconds,

Thus, we get a line having positive slope.

Therefore, Below graph shows his motion,

Answer 2

I found the missing graphs but I only attached the correct graph that answers the above question.
I also made notes in the image. Pls. see attachment.