The Physics PHYA2 thread! 5th June 2013

Did anyone notice that the drawing graph question was the same as Q3b on this June 2009 paper? http://www.gcephysics.com/past-papers/AQA-PHYA2-W-QP-JUN09.PDF

Anyways, this is my proposal for the graph. The elements they are looking for (I think) although can be exaggerated a little are...
1. A straight line to the oil ( or a very slight bend towards the end, as you never know, the air could be really humid, etc...)
2. Sudden drop in acceleration, can be over a small period of time I guess, but mine was vertical
3. Terminal velocity reached in oil, quicker, and lower than that in air ( and then maybe a sudden drop to finish?)

I think this is 3 but, you never know...
I've exaggerated a little, but as I said, depending on conditions I don't see why this couldn't happen...


Posted from the TSR iPad app

Nope it was accelerating and acceleration decreased to 0. I completely messed up and said the deceleration was decreasing like in a past paper

Yeah I knew it had come up before and I could remember doing it so I was very happy.


I think they're going to want a line of constant gradient up to T1, a sloping drop off as it decelerates in the oil and then a flat line to show terminal velocity (and then possibly a vertical line to 0 when it hits the bottom). Or, possibly a line which curves upwards into the flat if you want to argue that the ball would accelerate even in the oil which is unlikely but could be given.


I'd think those marks will be around 94-96 UMS. With your Unit 1 I'd think you'll get an A overall.

It was the same question as a past paper. It is definitely deceleration

0.44N

Edit: sorry realised what you just said.

i think they said that the diameter of a sphere metal ball was $2.2\times10^-2$ and that the density was $8100 kgm^-3$ and you had to use $v = \frac{4}{3}\pi(\frac{D}{2})^3$ and then you use $m = vp$ then final answer you then times by 9.81 to get 0.44N

For the question on define frequency ..

i said it is the reciprocal of time period .. but also i wrote something wrong like it the number of waves passing a point per cycle... will they ignore the second bit ... and will i get the mark.

That's what I thought but think about it the gradient is acceleration and its ALWAYS positive until it levels off. If it decelerated the gradient would be negative

It's not, it's negative when it hits the oil
http://www.gcephysics.com/past-papers/AQA-PHYA2-W-QP-JUN09.PDF
3B

Anyways, this is my proposal for the graph. The elements they are looking for (I think) although can be exaggerated a little are...
1. A straight line to the oil ( or a very slight bend towards the end, as you never know, the air could be really humid, etc...)
2. Sudden drop in acceleration, can be over a small period of time I guess, but mine was vertical
3. Terminal velocity reached in oil, quicker, and lower than that in air ( and then maybe a sudden drop to finish?)

I think this is 3 but, you never know...
I've exaggerated a little, but as I said, depending on conditions I don't see why this couldn't happen...


Posted from the TSR iPad app

got phya4 in 7 days, i SERIOUSLY need to smash that, gonna need atleast 90 UMS :'(

It's not, it's negative when it hits the oil
http://www.gcephysics.com/past-papers/AQA-PHYA2-W-QP-JUN09.PDF
3B

That's what I thought but think about it the gradient is acceleration and its ALWAYS positive until it levels off. If it decelerated the gradient would be negative

For the graph about the ball and the oil I think it is debatable. Surely the ball would continue to accelerate in the oil for only a short period of time and then level off for terminal velocity?