Recent content by mklein

Yes please - without too much (any !) calculus !

Thanks rcgldr So how does this link with the equation: F=mw^2R (w=angular frequency) Suppose we halve R. Therefore, as you say, F doubles. So does this mean that W^2 must quadruple, so therefore w doubles?

Indeed ! Thanks again Matt It would be fun to pose the question to my a-level class - but then not so fun when they give up and ask for the answer ! Just looking up the idiomotor effect - not familiar with that !

Definitely not doing this for fun ! I am not entirely sure what the force condition is when a rubber bung on a string wraps itself around a finger ! I also admit that I am very rusty on the angular momentum it's equations - simply because it is not something I teach and I haven't looked at it...

Your quote is from the "teaching notes" section, I am referring to the "procedure" section. Sorry to be pedantic ! [FONT="Lucida Console"]"a Whirl the bung fairly gently in a horizontal plane above the head. b Allow the string to wrap round a finger. If the bung is whirling slowly at...

Just in case you didn't notice it, on the practicalphysics.org website it was actually the reference to speed in the procedure part b which I was initially confused about

Hi Simon I used the word "apparently" because the websites describing the demo state that we should be able to notice an increase in speed. Here is somebody with an MIT phd also stating that the speed should increase: http://www.physlink.com/education/askexperts/ae154.cfm I am still unsure !

Thanks Neandethal. This does indeed make sense i.e. it is the frequency which increases and NOT the speed. Unfortunately I have seen some sites which say that the speed increases, including this quite respectable site...

Dear forums Hello. I teach physics, and whilst I think that my knowledge is fairly sound, once every now and I then I encounter something which baffles me like so... In a simple demo of circular motion, a rubber bung is whirled around the head in a horizontal plane. If the bung is...

Dear pmsrw3 and micromass These are two very good suggestions, and I shall look into them, thank you. I can just about handle this level of maths! Thanks Matt

Dear all I am looking to write my own computer program for a Fourier transform. However my maths is very rusty and I will need to recap some things. I am struggling a little bit to recall the rules for the period of sines (or cosines) when they are MULTIPLIED. I haven't had much luck...

Thank you Doc Al, and everybody else that has contributed. You really have been very helpful. The equations in the last post are obviously the cases you are usually asked about in your school/college exams. Interesting how I have turned "full circle" going from those equations in class...

This makes sense, thank you. And this deducing you refer to. Would that be something like this: If F is the centripetal force (m*v*v / r), and N is the normal: At 6 o'clock : F = N - mg At 12 o'clock: F = N + mg At 3 o'clock : F = N So the track produces the right amount of...

You may have just helped me by asking that. I was thinking that, if you resolve forces for a stationary block on a slope, weight mg, you find that: the component of the weight parallel (down) the slope is mgsin(theta), and perpendicular to the slope it is mgcos(theta). So it is probably...

Thank you Doc Al This does make sense when you say that only a component is required towards the centre of the circle ... ... BUT ... I am fairly sure the resultant is parallel/tangential to the slope. So surely this would never have a component towards the centre?