Rotational Mechanics

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put up a solution and will check it

Not tried it just yet, but I will do later. It's just that the last line 'in terms of m and g' bothered me. Would there not have to be another length in there somewhere?

(edited 8 years ago)

Reply 21

TeeEm

Original post by A Slice of Pi

Not tried it just yet, but I will do later

yes there is a typo ... I checked in my written solution and I have 4/3 mga

Reply 22

A Slice of Pi

Original post by TeeEm

yes there is a typo ... I checked in my written solution and I have 4/3 mga

I get this also

sol1.pdf477.2KB

Reply 23

TeeEm

Original post by A Slice of Pi

I get this also

your mechanics is too good ...
here is my solution

Original post by TeeEm

your mechanics is too good ...
here is my solution

Neat and nice
thank you :smile:

Reply 25

TeeEm

Original post by depymak

Neat and nice
thank you :smile:

mine is supposed to be neat and nice....
"A Slice of Pi" is not ....

Reply 26

stochasym

Original post by TeeEm

mine is supposed to be neat and nice....
"A Slice of Pi" is not ....

I meant yours (TeeEm)

Reply 27

atsruser

Original post by TeeEm

we have to wait for the Mechanics master-kid .
(Hopefully I catch him !!!, as he looks unbeatable at the moment)

I get 4/3 mg (I could be wrong)

You are probably right. I misread your question - I thought that it said that there was a couple acting contrary to the torque generated by the falling mass - in fact, it's a frictional couple, so it can't be analysed the way I was going about it - you need an energy argument. (I also used h instead of 2h when calculating the final speed of the falling mass but that's trivial). I'll have to start taking more care with these questions.

Reply 28

TeeEm

Original post by atsruser

I am giving up ...
A slice of pi made mince meat of this one too ...

Reply 29

atsruser

Original post by TeeEm

I am giving up ...

Err, why? Confused.

Reply 30

TeeEm

Original post by atsruser

Err, why? Confused.

this A level kid does everything I throw at him ...
polars, intrinsic, rotations, variable mass ....

Reply 31

A Slice of Pi

Original post by TeeEm

this A level kid does everything I throw at him ...
polars, intrinsic, rotations, variable mass ....

But why is that a bad thing?

(edited 8 years ago)

Reply 32

TeeEm

Original post by A Slice of Pi

By why is that a bad thing?

I am very busy in the next 2 days but I am making a question with a marble rotating inside a cone and moving up and down ....
Start revising ...

Reply 33

A Slice of Pi

Original post by TeeEm

I am very busy in the next 2 days but I am making a question with a marble rotating inside a cone and moving up and down ....
Start revising ...

Fair enough, but as long as its next week because I'm not going to be able to do any maths this weekend as I have a fair bit of chemistry work to do...

Reply 34

atsruser

Original post by TeeEm

this A level kid does everything I throw at him ...
polars, intrinsic, rotations, variable mass ....

I'm taking your questions too casually - trying to do them on scraps of paper while doing other stuff. I'm going to up my game from now on.

Reply 35

TeeEm

Original post by atsruser

I'm taking your questions too casually - trying to do them on scraps of paper while doing other stuff. I'm going to up my game from now on.

Reply 36

atsruser

Original post by TeeEm

When it comes to me and your mechanics questions, Mr TeeEm, from now on, it's no more Mister Nice Guy.

Reply 37

FriendlyPenguin

Original post by TeeEm

this A level kid does everything I throw at him ...
polars, intrinsic, rotations, variable mass ....

Pi is an A-level kid?

Puts me to shame... :frown:

Spoiler

Reply 38

TeeEm

Original post by Mathemagicien

Pi is an A-level kid?

Puts me to shame... :frown:

Spoiler

so (s)he claims

Reply 39

atsruser

Original post by atsruser

Am I being stupid?

Spoiler

Given someone has repped this, I ought to point out that the argument is wrong (I forgot about the jerk => inelastic) - you can see the correct approach further down the thread. (Conservation of AM to start with, which is always true, so we don't have to worry about elastic/inelastic processes).