How Does Relative Motion Affect What Barbara Sees While Rollerblading?

[gamer1319]

This is a practice question.

If somebody could help me with this practice question, I'd really appreciate it.

Two friends, Barbara and Neil, are out rollerblading. With respect to the ground, Barbara is skating due south. Neil is in front of her and to her left. With respect to the ground, he is skating due west. (a) Does Barbara see him moving toward the east or toward the west? (b) Does Barbara see him moving toward the north or toward the south? (c) Considering your answers to parts (a) and (b), how does Barbara see Neil moving relative to herself, toward the east and north, toward the east and south, toward the west and north, or toward the west and south? Justify your answers in each case.

 

[berkeman]

This is a practice question.

If somebody could help me with this practice question, I'd really appreciate it.

Two friends, Barbara and Neil, are out rollerblading. With respect to the ground, Barbara is skating due south. Neil is in front of her and to her left. With respect to the ground, he is skating due west. (a) Does Barbara see him moving toward the east or toward the west? (b) Does Barbara see him moving toward the north or toward the south? (c) Considering your answers to parts (a) and (b), how does Barbara see Neil moving relative to herself, toward the east and north, toward the east and south, toward the west and north, or toward the west and south? Justify your answers in each case.

Welcome to the PF.

Sounds like a good practice problem. But as with all problems posted here, you need to give us your answers first, before we can offer tutorial help.

What are your initial answers for each question, and what are the reasons for the answers you chose?

 

[gamer1319]

Sorry, didn't know that.

Here are my initial answers:

Two friends, Barbara and Neil, are out rollerblading. With respect to the ground, Barbara is skating due south. Neil is in front of her and to her left. With respect to the ground, he is skating due west.

(a) Does Barbara see him moving toward the east or toward the west? I drew the FBD and assumed that she sees him moving towards the west.

(b) She sees him moving down, thus south

(c) Barbara doesn't seel Neil differently because east and north, east and south, and west and north are opposite vectors. (ex. if they were both north at same speed, she would seem him at 0m/s)