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# M4 Relative Motion Diagrams watch

1. Is there an easy way to go about drawing diagrams for these relative motion questions?

I can never seem to get them right and end up calculating wrong angles and velocities. Especially Question 8 and Question 10 in the scan below.

2. Just tagging some folks:
Spoiler:
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3. (Original post by Euclidean)
Is there an easy way to go about drawing diagrams for these relative motion questions?

I can never seem to get them right and end up calculating wrong angles and velocities. Especially Question 8 and Question 10 in the scan below.

I pass as I am very busy at present but I would suggest to look at similar questions in my example book

The earliest I can help is Monday (I am working solid this weekend)
4. (Original post by TeeEm)
I pass as I am very busy at present but I would suggest to look at similar questions in my example book

The earliest I can help is Monday (I am working solid this weekend)
Brilliant, thank you very much!

5. (Original post by Euclidean)
Brilliant, thank you very much!

at first glance of your questions there are 3 or 4 of very similar style
All the best!
6. Attachment 508513508515
(Original post by TeeEm)
at first glance of your questions there are 3 or 4 of very similar style
All the best!
I was able to solve the first 5/6 questions from your booklet with no problem. I intend to do the majority of them next week.

I am still stuck on question 10 from the initial post. It's a question from the old Heinemann textbook. I've attached a picture of the question and my shoddy diagram.

Would you be able to give me a clue or tell me whether my diagram is wrong if you get the time?

Edit: There's a mistake on my diagram, the last equality the sine term should be positive

Attached Images

7. (Original post by Euclidean)
Attachment 508513508515

I was able to solve the first 5/6 questions from your booklet with no problem. I intend to do the majority of them next week.

I am still stuck on question 10 from the initial post. It's a question from the old Heinemann textbook. I've attached a picture of the question and my shoddy diagram.

Would you be able to give me a clue or tell me whether my diagram is wrong if you get the time?

Edit: There's a mistake on my diagram, the last equality the sine term should be positive

I can look at it tomorrow as I am teaching all day today
8. (Original post by Euclidean)
Attachment 508513508515

I was able to solve the first 5/6 questions from your booklet with no problem. I intend to do the majority of them next week.

I am still stuck on question 10 from the initial post. It's a question from the old Heinemann textbook. I've attached a picture of the question and my shoddy diagram.

Would you be able to give me a clue or tell me whether my diagram is wrong if you get the time?

Edit: There's a mistake on my diagram, the last equality the sine term should be positive

The actual velocity of the wind is obtained by adding the velocity of the observer to the apparent velocity of the wind. Looking at it that way, your arrows aren't working. The arrows of the observer's velocity and the apparent wind velocity should follow each other round, with the actual wind velocity arrow being the resultant.

Having got that right, you have to fiddle around with the lengths of the sides of the triangles to make the direction of the actual wind velocity go in approx the same direction. I managed it by having the apparent wind velocity being quite large compared with the observer's velocity.
9. (Original post by Euclidean)
Attachment 508513508515

I am still stuck on question 10 from the initial post. It's a question from the old Heinemann textbook. I've attached a picture of the question and my shoddy diagram.

My diagram is attached, with the two triangles stuck together.
Attached Files
10. wind triangle 2.doc (41.5 KB, 57 views)
11. (Original post by tiny hobbit)
My diagram is attached, with the two triangles stuck together.
Apologies for the slow response:

I finally solved the question going off of your diagram. Do you have any tips to help draw the diagrams?

Many thanks
12. (Original post by Euclidean)
Apologies for the slow response:

I finally solved the question going off of your diagram. Do you have any tips to help draw the diagrams?

Many thanks
Nothing very concrete. On the apparent wind questions, I usually find myself drawing the separate triangles several times, varying the unknown lengths, until I can make the actual wind arrow go in the same direction on both triangles. Then I stick the two triangles together and the geometry of the thing becomes clear.
13. (Original post by tiny hobbit)
Nothing very concrete. On the apparent wind questions, I usually find myself drawing the separate triangles several times, varying the unknown lengths, until I can make the actual wind arrow go in the same direction on both triangles. Then I stick the two triangles together and the geometry of the thing becomes clear.
Thanks for all the help

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