Which of the following is vector and which is scalat

  • Thread starter vkash
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which of the following is vector and which is scalar?????

angular velocity and angular acceleration are __________ quantity..
my answer is vector. am i correct.
here i am considered about only rotational motion.
somewhere in book it is written as non vector. that's why i am asking it.
 
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Answers and Replies

  • #2
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Mod node:

The longish, off-topic, and not all that helpful discussion on angular displacements has been moved to its own thread, [thread]590427[/thread].



Hey vkash.

This is a good one.

See, instantaneous angular displacement is a vector.

Average angular displacement is not a vector.


What does this information tell you about instantaneous angular velocity and acceleration.?
a car is moving in x direction of reference frame with a velocity of 50ms-1. IS it vector or scalar...? i think that's vector.

this is question in my last FIITJEE test. in that test it was question in matrix match, in one side there were these two quantities and in other side their was an option of vector quantity.,

What does it tell you about average angular velocity and acceleration?

In exam it has never been mentioned that either a thing is vector or scalar. but i always assume that it is vector to approach my question..


Do you know why instantaneous angular displacement is a vector while average angular displacement is not?
i don't know <><><>
i think this might be because of these formulas. L=Iω , L[angular momentum] is vector I[moment of inertia] is not a vector so w[angular velocity] must have been a vector quantity.. IT seems like foolish answer but i am not getting any other answer for this.
 
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  • #3
cepheid
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You are making this way too complicated. Just look up the *definitions* of these two quantities to see if they are vector or scalar.
 
  • #4
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You are making this way too complicated. Just look up the *definitions* of these two quantities to see if they are vector or scalar.

http://en.wikipedia.org/wiki/Angular_velocity
They mention it in 1st line. It is a vector quantity. similarly it's derivative with respect to time will also a vector.
 
  • #5
D H
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The answer is "it depends". In particular, it depends on the dimensionality of the space and whether one considers pseudovectors to be vectors.

In the context of rotations in three dimensional space, angular velocity and angular acceleration can be treated as vectors. Angular velocities and accelerations in ℝ3 have an additive inverse, add, and can be multiplied by a scalar. In this sense they are vectors. They do not act like position and velocity vectors upon reflection. In this sense they are pseudovectors. However, pseudovectors are vectors if you look at them from the context of being a member of a vector space.

Angular velocity and angular acceleration in any dimensional space other than ℝ3 are not vectors. They are instead bivectors or 2-forms. However, this FIITJEE test is apparently with regard to engineering problems. Engineers worry primarily about problems in our 3D world, where angular velocity and angular acceleration are vectors.


Without further details about the question at hand, I would agree that you have the correct answer, vkash.
 

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