Edexcel Unit 3 (IAL): Exploring Physics, WPH03 (26th January 2016)

Not sure. Maybe 1 mark, there is a very similar question in Jan or June 15..

I dont think you needed to plot a graph ...they didnt mention to use a graphical method like past years..and also any definition including a graph ques. would have been for atleast 4 marks..just using the efficiency eqn. Would have done..

Well, I thought about writing the equation only, (I wrote it too though) including the graphical method.

Was confused for 4 marks. lol

Check paper January 2012 for example.

Oh just checked the jan 2012 there it was mentioned "straight" line of best fit..but this time its was just the line of best fit isnt it?..can anybody confirm though??..

and also at the front it was written that you may need a ruler and which was only specifically needed for drawing the straight line for that ques. throughout the whole paper in the jan 2012 one...which wasnt the case for this paper this time..

Haha although i put on a straight line today......but there will be all confusions regarding this ques. Up and until the ms gets released..

But one thing for certain the gb will be low for the one half of the studs..

I drew best fit but it looked crap so I went for the curve.

I got 6.5 * 10^6 as well and that's definitely right. I said that the extension was due to force only and not thermal expansion, somebody else said area is constant.

Actually, if you look at it, you've got the first three points above the line of best of fit and the next three below. Was that what you got? But for some weird reason I got the answer for the area as 11.8

Edit: @Zainat0987 it was supposed to be a straight line.

I drew a curve.

I'm pretty sure it was supposed to be a curve, since there is no direct relationship of force against extension for a rubber.
For a rubber, the force against extension graph is a curve.

B-but you see it has got to be a smooth curve correct? This one looked spooky, no way it could have been a curve

B-but you see it has got to be a smooth curve correct? This one looked spooky, no way it could have been a curve

B-but you see it has got to be a smooth curve correct? This one looked spooky, no way it could have been a curve

Motor Experiment, even though experiments are marked (holistically and not really pin-point to the MS)

This is just the summary of what, I wrote (Not exact):

Quantities to be measured:

Height, Time, Current.

Two Quantities & Apparatus:

Height - Metre rule - +-1mm
Time - Stop watch - +- 0.01 s

Repeat?

Yes, repeat to get average value, and more reliable / accurate result etc...

How to obtain Efficiency?

Plot a graph of Power output against power input, gradient/efficiency = (mgh/t) / (V*I) etc..

Uncertainty:

Friction in the axle, so energy dissipated and power output would decrease.

Safety

Electric shock etc. (any appropriate comment)

Yes, it has to be a smooth cuve - hence why you ignore the values that add kinks to the curve.

I ignore the last point as it got too high and i made a smooth curve

I drew a curve.

It was not a smooth curve it was something like an S shape. Thats like the Force-extension graph for rubber (you can find the graph in hodder book). If you used all the points the graph looked like this exactly (the picture is the google image search result for rubber Fx graph)

I am back !! I calculated the work according to the line of best fit which is usually the right way to get similar stuff in the past papers. What did you get for stress and strain though ? I got 650000 and 2.3 and my assumption was that the area is constant.

They asked for the best fit "line" so i continued with a straight but the points on the the graph were indeed a bit awkward i also thought of going for a curve at first..

Btw what was the stress value 6.5 * 10^6?..and what could be the assumption ?

I drew best fit but it looked crap so I went for the curve.

I got 6.5 * 10^6 as well and that's definitely right. I said that the extension was due to force only and not thermal expansion, somebody else said area is constant.

That's a smooth curve.

A smooth curve means continuous and non-polygonal.

But you don't need to ignore any points. My points matched perfectly to make the curve

Mine looks exactly like the picture you describes and I ignored 2 points.