Higher Level Physics

sock puppet

sock puppet wrote: »

I got around 420 years iirc.

Yah that sounds right. I got 421 or 424 or something.

likely_lass

OK this was only worth like 4 marks but it really annoyed me, for the velocity time graph of the scateboarder - he was going at 12.2m/s when he reached the bottom on the slope and then continued at 10.5m/s to the curved bit

when the hell did he decelerate was it a typo???

ciaran brady

yea it was a typo

papu

likely_lass wrote: »

OK this was only worth like 4 marks but it really annoyed me, for the velocity time graph of the scateboarder - he was going at 12.2m/s when he reached the bottom on the slope and then continued at 10.5m/s to the curved bit

when the hell did he decelerate was it a typo???

linka looked like this
12.___
.../10.5\___
../..............\
./........0.......\

thats what i got anyway

dont think it was a typo there were no corrections , and if it was a typo we get full marks anyway

ciaran brady

wats a typo neway?

Jack Sheehan

ciaran brady wrote: »

americium isnt in the periodic table is dat a valid answer?

http://www.webelements.com/americium/

umm...

timmywex

ciaran brady wrote: »

americium isnt in the periodic table is dat a valid answer?

Its because it is an isotope is the answer

papu wrote: »

linka looked like this
12.___
.../10.5\___
../..............\
./........0.......\

thats what i got anyway

dont think it was a typo there were no corrections , and if it was a typo we get full marks anyway

Yeh thatd be right. Wasnt a typo, you have to assume the deceleration.

smndly

Did anyone get the height of the skater to be 5.01m?

And it wasnt a typo. He decelerated due to the friction.

Tractorgal xx

i hated that exam

errlloyd

smndly wrote: »

Did anyone get the height of the skater to be 5.01m?

And it wasnt a typo. He decelerated due to the friction.

Hmm no I don't think so, the question very specifically said "friction experienced on the ramp"

Like needless to say, velocity time graphs are ****.

(Btw anyone see predictions, nailed the experiments, yummy)

On the topic of the experiments, did anyone put down "less height" as a way to minimize air resistance. Truth is, I wasn't thinking and I put down more, because it lowers percentage error.

papu

errlloyd wrote: »

Hmm no I don't think so, the question very specifically said "friction experienced on the ramp"

Like needless to say, velocity time graphs are ****.

(Btw anyone see predictions, nailed the experiments, yummy)

On the topic of the experiments, did anyone put down "less height" as a way to minimize air resistance. Truth is, I wasn't thinking and I put down more, because it lowers percentage error.

i said use a small heavy ball... or else do it in a vacuum

errlloyd

papu wrote: »

i said use a small heavy ball... or else do it in a vaccum

I said them too !!

It just I am worried I will lose marks, because I wasn't just incorrect, I was full on wrong!!

Like if you drop from higher the ball goes faster and therefore more air resistance acts on it.

Tractorgal xx

errlloyd wrote: »

I said them too !!

It just I am worried I will lose marks, because I wasn't just incorrect, I was full on wrong!!

Like if you drop from higher the ball goes faster and therefore more air resistance acts on it.

i said do it in a vaacum and use a really smooth ball...

a guy in my class said oil the ball :pac:

errlloyd

Lol Galileo domination

http://video.google.com/videoplay?docid=6926891572259784994

celtic723

errlloyd wrote: »

Hmm no I don't think so, the question very specifically said "friction experienced on the ramp"

Like needless to say, velocity time graphs are ****.

(Btw anyone see predictions, nailed the experiments, yummy)

On the topic of the experiments, did anyone put down "less height" as a way to minimize air resistance. Truth is, I wasn't thinking and I put down more, because it lowers percentage error.

that's correct with the air resistance as far as i know because the higher it is dropped from means the longer it has for air resistance and weight to cancel each other out meaning the ball travels at the speed of gravity without the act of air resistance impending on its fall. that's what i said anyway and i'm pretty sure i seen that in the book somewhere too.

Tractorgal xx

galeileo.. some man ha

Fince

Tractorgal xx wrote: »

i said do it in a vaacum and use a really smooth ball...

a guy in my class said oil the ball :pac:

i said polish the ball?

Tractorgal xx

that isnt as bad as oil i guess!!!!!!!!

likely_lass

heavier ball & polish the ball ?

smndly

Anyone remember what they got for the max height of the skateboard??

I said small ball that is heavy ie a high density ball. I also said keep the distance small

I just said keep the distance between the ball and the trap door to a minimum, and then I just talked about Stokes law (i.e. that air resistance is proportional to the velocity squared). For the second precaution I said use a small polished ball.

Edit: For the height I got 5.45 metres or something like that (that's above the ground). Which is about .45 metres above the top of the quarter pipe ramp thing.

Prowetod

smndly wrote: »

Anyone remember what they got for the max height of the skateboard??

I said small ball that is heavy ie a high density ball. I also said keep the distance small

1.75 m probably wrong though!

Heggy

I got about 5.4m for the max height.
For the air resistance one, i thought about putting down use less height, but that makes the experiment more inaccurate overall doesn't it, because of the time escaping from the magnet, and the way you always have to take the smallest value.

I just said use a smooth ball, and make sure there are no draughts, though the heavy ball and vacuum would have been better.

Fince

smndly wrote: »

Anyone remember what they got for the max height of the skateboard??

didn;t write it down but somewhere in the 5.2 to 5.6 region.

did people do it using potential energy and kinetic energy? or what alternative?

errlloyd

I'm not 100% but I don't think a smooth ball would actually help.

Why does a golf ball have dimples, more aerodynamic right? Or is it to do with spin?

Fince

Fince wrote: »

didn;t write it down but somewhere in the 5.2 to 5.6 region.

did people do it using potential energy and kinetic energy? or what alternative?

I did it in a far too complicated way.

I used the conservation of mechanical energy ([latex]\mbox{mgh} = \frac{1}{2}\mbox{m}\mbox{v}^2[/latex]) to find what speed it would be doing at the top of the ramp, then I just used [latex]\mbox{v}^2 = \mbox{u}^2 %2B \mbox{2as}[/latex] (letting a = g) to find its vertical height from the top of the ramp. It worked out at something like 5.2 - 5.4 metres above the ground.

I just had to try the new Latex add-on for boards for equations. Works pretty well!

errlloyd

I did the same as Jammy there, except I just used the equations of motion from the start. I think thats actually acceptable on physics, but on applied maths I would get raped for it...

Alexl

There was no typo in the speed time graph, he deccelerated because he went up a quarterpipe. Its a stupid question though because his his decelleration will not be uniform because as he travels up the quarterpipe more and more of his weight will start to act against him.....
I got 5.6 something for the height, using the energy formula.
Does that mean he doesnt leave the ramp, because the ramp was 10m high.

ironclaw

likely_lass wrote: »

heavier ball & polish the ball ?

Drop from a low height

Take multiple readings for one height, take the smallest time. The ball is falling under gravity nothing should speed it up, as such the smallest reading is the best one to take.

As for polish the ball, I don't know, its a ball bearing so any effect of polishing would be extremely negliable.

You could have said place it in a vacumn, it never said it had to be a pracical suggestion! :pac:

There was no typo in the speed time graph, he deccelerated because he went up a quarterpipe. Its a stupid question though because his his decelleration will not be uniform because as he travels up the quarterpipe more and more of his weight will start to act against him.....
I got 5.6 something for the height, using the energy formula.
Does that mean he doesnt leave the ramp, because the ramp was 10m high.

Well, technically that is the vertical height, as in if the circle didn't exist. You couldn't have figured out the actual height (because if you think about it he was on a slope) given the maths and data

His decelleration will be unifrom however. He will slow down at a steady rate given its a circle and the effect of gravity will be proportional.. etc etc...

-ilikeshorts

The dimples on golf balls are to keep them straight and to do with spin