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# Quick physics question angular velocity watch

1. isn't the formula for the instantaneous angular velocity and for the average angular velocity the same thing?

I don't see the difference - both are diff in theta/diff in time

pls pls help
2. (Original post by h26)

isn't the formula for the instantaneous angular velocity and for the average angular velocity the same thing?

I don't see the difference - both are diff in theta/diff in time

pls pls help
it's convention to use 'd' for infinitesimal amounts of change...
t1 - t0 might have been (but in this picture isn't) written as Δt... i.e. some measurable amount of time.

I'd say it's not really an important distinction unless you're using calculus
3. (Original post by Joinedup)
it's convention to use 'd' for infinitesimal amounts of change...
t1 - t0 might have been (but in this picture isn't) written as Δt... i.e. some measurable amount of time.

I'd say it's not really an important distinction unless you're using calculus
but the thing is that instantaneous angular velocity is a completely different thing to the average angular velocity especially when the acceleration is not zero. So surely they should have different formulas?
like if you had to work out the instantaneous angular velocity then how would you do it?
5. (Original post by h26)
but the thing is that instantaneous angular velocity is a completely different thing to the average angular velocity especially when the acceleration is not zero. So surely they should have different formulas?
like if you had to work out the instantaneous angular velocity then how would you do it?
TBH it's a related thing. After all the units of average angular acceleration are the same as the units for instantaneous angular acceleration so it shouldn't be too much of a surprise.

I think you'll only have to worry about constant acceleration at A level BUT if you can get a formula giving angular velocity as a function of time you'd do differential calculus on it with respect to t to get the formula for angular acceleration.

FWIW this isn't unique to angular acceleration - instantaneous linear acceleration would be dv/dt and so on for anything that changes over time.
6. (Original post by Joinedup)
TBH it's a related thing. After all the units of average angular acceleration are the same as the units for instantaneous angular acceleration so it shouldn't be too much of a surprise.

I think you'll only have to worry about constant acceleration at A level BUT if you can get a formula giving angular velocity as a function of time you'd do differential calculus on it with respect to t to get the formula for angular acceleration.

FWIW this isn't unique to angular acceleration - instantaneous linear acceleration would be dv/dt and so on for anything that changes over time.
Hey thanks a lot! So i guess for a level i just ignore instantaneous angular velocity as its above the level iam required to know about?
7. (Original post by h26)
Hey thanks a lot! So i guess for a level i just ignore instantaneous angular velocity as its above the level iam required to know about?
For simplicity, yes. They do what they say on the tin really, instantaneous gives the value of a quantity at a specific point, average gives you the, well, average value of a quantity over the entire time period you're looking at. If you go on to do a physics degree, the distinction between the two will be made apparent in the first term of the first year when calculus is no longer swept under the carpet as a concept only used in maths. I really think it should be included at least in Year 13 physics if not before
8. (Original post by Joinedup)
it's convention to use 'd' for infinitesimal amounts of change...
t1 - t0 might have been (but in this picture isn't) written as Δt... i.e. some measurable amount of time.

I'd say it's not really an important distinction unless you're using calculus
Isaac Newton invented physics, he also invented gravity and calculus. He also had bad teeth because he ate too many toblerone bars and lollies which used to get stuck to his sleeves, as is evident from his pic on the original £1 note. He also had a hairdo to shame Bon Jovi.

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