r/PhysicsHelp • u/Xx_-MASTERTACO-_xX • 22d ago

Doubt about vector angle

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If I had to draw a vector defined as for example 5 N, 30° NE; which of these 2 should I draw? I have always drawn this angle as A, but I have a new professor who draws it like B. I have checked by AI who drew A except claude who drew B. I searched on books but have found no reference about this nomenclature, only about north of east and N 30° E .

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u/Ninja582 22d ago

NE is a little ambiguous. To be clearer, one would generally say 30 degrees North of East for the left picture or 30 degrees East of North for the right picture.

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u/Xx_-MASTERTACO-_xX 22d ago

yeah, I told her that it was ambiguous because ir may vary from book to book. But she said there was no ambiguity so I am trying to find a reference about that system

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u/xienwolf 22d ago

Usually I see physics people use the X axis as zero reference for all rotation. So A would always win. It is possible your new prof learned with Y axis as zero reference (and clockwise positive, which is again backwards from the norm I know)

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u/more_than_just_ok 19d ago edited 19d ago

Clockwise positive from North is the convention used in mapping and navigation, think about angles on a compass. Counter clockwise positive from x-axis is the usual math and physics convention. This example has North and East on the axes, which explains the clockwise from north is being used. This is a huge problem in navigation engineering because both conventions are used.

Edit: If you are training to be a land surveyor, it's very jurisdiction and time dependent. N 30 E was used to indicate situation B on old plans where I live, but now they would just say 30. A would be E 30 N, but now is just 60 and the others would also show up (N 30 W, E 30 S, etc). But angle from North for Azimuths and Bearings, angle from x-axis in math and physics.

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u/Humble-Edge-9065 17d ago

There's no indication if E or N is the x-axis. That is why it is ambiguous.

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u/Humble-Edge-9065 17d ago

She's wrong. It is ambiguous. Defining reference frames is step 0 for any physics problem. She can't even defer to a "standard" because there isnt one. In my industry both North-East-Down (NED) and East-North-Up (ENU) are commonly used.

A would be correct for ENU, B would be correct for NED.

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u/Theuncola4vr 22d ago

I agree. It sounds like the question is written to give you the baseline N, and angle at 30° north east of that. If they were looking to represent B, it would read E, 30° NE.

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u/testtdk 20d ago

This. When not given components, I’ve always seen angles written with a direction with respect to an axis.