Edgefield 6091 4E PRELIM P2 2024 markschemeP2

Edgefield Secondary School 2024 Sec 4E Pure Physics PRELIM Exam Marking Scheme Page 1 Subject : 6091 Pure Physics Level : Secondary 4 Express Exam : 2024 Prelim Examination Paper : Paper 2 Note : -No mark is given if the answer has no unit or wrong unit. -Appropriate significant figures/ decimal places for each numerical answer, max 1 mark deducted for entire Paper 2. -ecf marks are only given if they satisfy certain conditions indicated in the Remarks. Paper 2 Qn SECTION A [Workings / Calculations / Methods] Marks / Remarks 1a arrow(head) on chain pointing to the right vertical arrow downwards and part of arrow touching or within rectangle of lights or direction of arrow in (i) and (ii) correct (by eye) 1m 1b scale given (must have unit of cm:N or cm/N or N:cm or N/cm) correct triangle or rectangle (might be implied) and correct resultant (compulsory e.c.f. from (i) or (ii): i.e. correct diagonal according to candidate’s (i) and (ii)) 272 ≤ candidate’s value ≤ 283 N 1m scale 1m correct length/dir weight 1m correct diagram and direction of resultant force Total = 4 m 2a Centre of gravity of any object is defined as the point through which its whole weight appears to act. 1m 2b 2nd quadrant 1m 2c When the centre of gravity is directly above the finger (pivot), the line of action of the weight of the disc lies within the finger. There will be no net moment about the finger and the disc will not topple. Or When the centre of gravity is directly above the finger (pivot), the 1m 1m

Edgefield Secondary School 2024 Sec 4E Pure Physics PRELIM Exam Marking Scheme Page 2 Qn SECTION A [Workings / Calculations / Methods] Marks / Remarks perpendicular distance from the finger to the line of action of the weight of the disc is zero. There will be no net moment about the finger and the disc will not topple. Or When the centre of gravity is not directly above the finger (pivot), the line of action of the weight of the disc lies outside the finger. There will be a moment due to the weight of the disc about the finger that causes the disc to topple over. 2d m = 450 g (2 sf) 1m for correct workings 1m for correct ans/unit 2e OR 1m Total = 7 m 3a i (p =) F/A or 12 000/0.048 = 2.5 × 105 Pa 1m for correct workings 1m for correct ans/unit 3a ii (F =) pA = 12 000 x 0.14 = 35000 N 1m 3b atmospheric pressure or friction (between cylinder and piston/oil) (accept bubbles (of air) in oil or viscosity of oil) 1m 3c (W.D. =) F × d or 12 000 × 0.065 = 780 J 1m for correct workings 1m for correct ans/unit Total = 6 m New hole is twice the size of 1 small hole

Edgefield Secondary School 2024 Sec 4E Pure Physics PRELIM Exam Marking Scheme Page 3 Qn SECTION A [Workings / Calculations / Methods] Marks / Remarks 4a geothermal 1m 4b i (E =) mcθ = 1000 × 4200 × 80 = 3.4 × 108 J 1m for correct workings 1m for correct ans/unit 4b ii  steam condenses or steam changes from gas to liquid  latent heat given out/ released/ lost from internal store  particles come closer together or potential energy of particles decreases or bonds being made 1m 1m Total = 5 m 5ai horizontal ray continued to bottom of I 1m 5aii 2.4 cm 1m 5aiii any two other rays drawn, e.g. through centre of lens 1m 5bi rays go to / meet at image or can be formed on a screen 1m 5bii image height / object height or image distance / object distance 4.0 1m for correct working/ans/unit Total = 5 m 6a The brush is charged by friction with the floor. The dust and ash will be induced by the brush to carry opposite charges. Opposite charges attract so they are pulled by the electrostatic attractive force created by the brush 1m 1m 6b Carpets and wood are insulators. The brush will be charged by friction when rubbing against the floor. 1m 1m 6c The electrostatic sweeper is quieter than an elecric vacuum cleaner There is no need to use electricity, which causes the release of greenhouse gases such as carbon monoxide, more environmentally friendly 1m Total = 5 m 7a i R =1500  (2 sf) 1m for correct workings 1m for correct ans/unit 7a ii I= V/R = 4.5/1500 = 0.0030 A (2 sf) 1m for correct workings 1m for correct ans/unit 7b i increases and resistance of LDR decreases 1m 7b ii does not change and resistance / e.m.f. does not change / not affected by LDR 1m Total = 6 m 8a i 0.20 kWh (2 sf) 1m 8a ii I = P/V = 40/230 = 0.17 A (2 sf) 1m for correct workings 1m for correct ans/unit 8b i To disconnect from live, high voltage, when appliance is switched off 1m 1m 8b ii if one lamp fails the other still works 1m Total = 6 m 9ai force on PQ / wire or PQ / wire moves force / movement out of page / outwards / towards observer (Ignore upwards) 1m 9aii force / speed / acceleration greater 1m 9b i change in field / flux (in coil) or field (lines) cut coil / wire produced an induced emf across coil 1m 9b ii more turns or stronger magnet or move magnet faster 1m

Edgefield Secondary School 2024 Sec 4E Pure Physics PRELIM Exam Marking Scheme Page 4 Qn SECTION A [Workings / Calculations / Methods] Marks / Remarks 9b iii (current in coil) produces magnetic field / poles N pole created at right-hand of coil or repels magnet / field in opposite direction 1m 1m Total = 6 m 10a swimming direction towards left - Water resistance opposite to swimming direction - Forward force (thrust) from water on swimmer, same as direction of swimming 1m 1m 10b When the swimmer’s hand pulls backward, an action force is exerted on water, backwards. By Newton’s Third Law of motion, water exerts a forward reaction force on the swimmer’s hand, equal in magnitude 1m 1m 10c With more volume of water and hence larger mass of water, the force exerted by the water on swimmer is larger. With a larger force on swimmer, and minimized water resistance, the swimmer can accelerate more. 1m 1m 10d When the forward force is greater than the water resistance force, there will be a forward resultant force. By Newton’s Second Law, since resultant force is the product of mass and acceleration, the resultant force will lead an acceleration of the swimmer. Accept: resultant forward thrust for 1st mark. Reject: forward thrust creates/causes/ equal to resultant force 1m 1m 10e Work done on water increases. Since work done is product of foce and displacement, a longer S path has larger displacement and larger work done on water. 1m 1m Total = 10 m 11a i diagram with GM tube or other detector, source and absorber between count/reading used in experiment ,repeat to take average reading alpha stopped by paper/card /2–10 cm air )) between 2 mm and 2 cm aluminium/metal/lead stops beta )) (some) gamma passes through aluminium/metal/lead )) 1m 1m 1m 1m 11aii any 2 points:  keep a distance, e.g. use tongs  point source away (from user)  use a barrier, e.g. wear lead apron  use a lead container to store/transport sources  use for a short time or monitor with film (badge) 1m, 1m 11a iii (otherwise) source decays/decreases (quickly) B1 or source has to be replaced often 1m 11b i top line of beta 0 Xe proton and neutron numbers both balance 1m 1m 11b ii gamma rays pass out of / are not stopped by body less chance of cell or gene damage / cancer / radiation sickness / mutation / ionisation (of body tissues) 1m Total 10 m

Edgefield Secondary School 2024 Sec 4E Pure Physics PRELIM Exam Marking Scheme Page 5 Qn SECTION B [Workings / Calculations / Methods] Marks / Remarks 12a work done per (unit) charge/coulomb/C or energy transformed per (unit) charge/coulomb/C property of a source (of electricity) or energy transformed to electrical energy per (unit) charge/coulomb/C 1m bi, ii ammeter in series/ voltmeter in parallel with lamp 1m, 1m ci Us