PHYA1 (Provisional, and very shaky) Mark scheme;Question 1 – Simple matter of working out forces and that stuff, efficiency question may cause problems though.
1) 6082N, which is 6100 to 2sf
(2)b) 9.5 degrees using arctan of 1000/6000
(2)c) Acceleration was 9.2ms^-2
(2)d) Can’t remember what this one was asking but I got 3.9x10^6 (not sure)
(2)e) I got 20.5% but I’m not sure as I’ve heard people give various answers
(3)Question 2 – Fairly straightforward question about projectiles.
2) Time taken was 0.55s
(2)b) The horizontal distance was 248m I think
(2)c) As both bullets have the same mass, S=ut will be smaller for the bullet with the lower horizontal velocity
(3?)-- Can’t remember if there was anything more to this question
Question 3 – Perhaps the best 6 marker they’ve ever given, very straightforward.
3) The ball begins to accelerate with a large acceleration as its weight force is (one of) the only forces acting as it begins to move. The gradient then begins to slowly decrease as the resistive forces begin to balance out the weight force. The ball finally reaches terminal velocity as the resistive forces balance out the weight force. Appropriate reference to Newton’s first law needed. Then the ball remains at that velocity, as there is no external force, give reference to Second Law.
(6)b) Initially a straight line indicating uniform acceleration, then a curve of decreasing gradient ending with the ball at terminal velocity.
(3)Question 4 – A decent question, I guess.
4) Weight of the ball was 0.44N (2sf) using volume of a sphere
which is given in the data sheet!!! (4)b)Hooke’s law states that force applied is proportional to the extension up to the limit of proportionality
(2)c) Gradient was roughly 1150/1100 Nm^-1needed
(3)d) Using the area of a triangle and then counting (roughly) 9 small boxes each of area 0.025 gave 1.08J
(3?)e) Straight line parallel to the first one but not finishing at zero as plastic deformation has occurred
(2)d) Plastic deformation means the object won’t return to its original shape/length once the load is removed
(2)f) Work is less as area under graph is less energy absorbed as heat and in permanent extension
(1)Question 5 – Wasn’t too bad..
5) Two conditions for TIR were an angle greater than the critical angle and moving from a medium of higher refractive index to lower
(2)b) Defining the frequency of a progressive wave. Just explain the equation?
(1)c) Speed of light in the object thing was 1.7x10^8
(2)d) Proof that the angle was about 31.8 degrees using Snell’s Law
e) Critical angle was 51.1 degrees using 1/sinc
(2)f) Undergoes TIR as (20+31.9) > 51
(2)e) TIR drawn (not sure about this one and the one above)
(1)Question 6 – Don’t even know, seemed cool..
6) First phase difference was 90 degrees or pi/2. Second was 270 degrees or 3pi/2
(2)b) Oscillation between maximum and minimum amplitude; i.e moves up and down
(2)c) Polarisation only occurs in transverse waves; mention something about plane of polarisation
(2)d) Define frequency
(1)e) 750m
(2)Question 7 – I may have flopped
7) All of the light has the same wavelength
(1)b) Can’t really remember – According to Frogs491 its ‘Fringes larger so intensity equal’ -- If this is the graph of intensity, then
(2)c) I too cannot seem to remember this
e) Last part; white at central maxima and very bright as all of the wavelengths converge at the centre; blue tinge closer to central maxima and red tinge further away; not sure about anything else.
(3)That’s all I can remember guys. I’ve probably omitted quite a few things so if anyone can spot any mistakes, let me know and I’ll make amendments
EDIT: I'm going to start adding in the marks for each question slowly so that should be half done soon. If anyone can remember what the marks are for each question please let me know! Thanks.
Also, I can't remember where the question about the weight of the ball goes but it was 0.44N and worth (4) marks...
Guys, we're missing 4 marks so if anyone can remember anything...