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Rotational Motion

by freshbox
Tags: motion, rotational
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freshbox
#1
Apr28-12, 07:43 AM
P: 284
Hi guys, I have a few doubts on Rotational Motion and hope someone can help me out.

This 3 formula is for finding angular velocity, angular acceleration and angular displacement right?
ω=ωi+αt
ω=ωi+2αδ
δ=ωit+1/2αt



And this 3 formula is for finding the linear velocity/acceleration/displacement in a angular shape?
s=rδ
v=rω
α=rα



Thanks.
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ZxcvbnM2000
#2
Apr28-12, 07:48 AM
P: 64
If you have no problems on linear acceleration then then only thing that changes in rotational motion is that u becomes ω , a becomes α , x becomes θ .

In both of your questions , the answer is yes .
freshbox
#3
Apr28-12, 07:58 AM
P: 284
Thank you ZxcvbnM2000 for the reply.


I want to ask can I use this equation v=rω to find the angular velocity as well?

ZxcvbnM2000
#4
Apr28-12, 09:00 AM
P: 64
Rotational Motion

yes of course as long as you know the linear velocity and the radius ;p
freshbox
#5
Apr28-12, 09:33 AM
P: 284
Ok thank you for the explanation and help.

Out of topic abit, if a rock is thrown downward from the top of a building, the velocity I can set it as -ve or +ve, and usually people set it to +ve for the working to be easier, am I right?
tiny-tim
#6
Apr29-12, 03:24 PM
Sci Advisor
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tiny-tim's Avatar
P: 26,148
hi freshbox!
Quote Quote by freshbox View Post
This 3 formula is for finding angular velocity, angular acceleration and angular displacement right?
ω=ωi+αt
ω=ωi+2αδ
δ=ωit+1/2αt
only for constant acceleration (just like the linear case)
And this 3 formula is for finding the linear velocity/acceleration/displacement in a angular shape?
s=rδ
v=rω
a=rα
s=rδ works only for constant ω

the other two always work
Quote Quote by freshbox View Post
if a rock is thrown downward from the top of a building, the velocity I can set it as -ve or +ve, and usually people set it to +ve for the working to be easier, am I right?
yes, so long as you're careful to adjust the sign of g to match
freshbox
#7
May1-12, 05:49 AM
P: 284
thank you tiny-tim for the explanation.


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