Mark scheme for IGCSE Physics (0625/3) – Extended Theory May/June 2001
1(a)(i)uniform acceleration1
(ii)uniform speed / terminal velocity1
2
(b) 20s1
1
(c)(i)force of gravity / weight downwards2
(ii)force of gravity / weight downwards and resistance / upthrust upwards2
3 (max)
(d)(i)yes
(ii) no1
1
(e)distance = area under graph / 0.5 x 5 x 481
= 120m1
2
2(a)momentum = mass x velocity / momentum = 800 x 201
= 16 000 1
kg m/s 1
2 (max)
(b)(i)momentum change = 16000 - 4000 1
force = 12 000/4 = 3000 N 2
(ii)deceleration = speed change / time 1
= 15/4 = 3.8m/s22
6
3(a)diagram showing balance and measuring cylinder1
suitable labels1
2
(b)balance reading for mass 1
two volume readings 1
2
(c)volume of stone from start and finish readings 1
density = mass / volume1
2
4(a)suitable random path1
1
(b)air molecules hit particles1
any two of:
molecules moving very fast / particles more massive / many hits
per particle / hits uneven2
2 (max)
(c)any two of: bigger movements / faster movements / air molecules faster2
2
5(a)heat input = power x time / 50 x 6001
temperature change for liquid = 45°C1
heat gained by liquid = mass x s x temperature change / 200 x s x 451
s = 30 000 / 9 000 1
= 3.31
J/(g K) 1
5 (max)
(b)(i)any two of: heat lost to atmosphere / temperature rise less / bigger by
reference to equation2
(ii)any one of: lagging / lid etc1
3
6(a)(i)any attempt shown to mark or measure critical angle1
critical angle = 40° (not 42°)1
(ii)incident angle at Q greater1
>40o (> than candidate’s value i.e. e.c.f.)1
4
(b)i = 32°, and r = 20° 1
R.I. = sin i / sin r 1
= sin 32° / sin 20° 1
= 1.551
4
7(a)direction sound (wave) is travelling1
1
(b)(i)pressure varies along sound wave / some particles closer than others1
(ii)very few particles at P / P is a rarefaction1
(iii)many particles at Q / Q is a compression1
2 (max)
(c)vibrates / oscillates / moves backwards and forwards1
along the direction of the wave1
2
(d)40 mm1
1
8(a)(i)current = power / voltage or = 0.6 / 1.51
= 0.4 A1
(ii)resistance = voltage / current or 1.5 / 0.4 (e.c.f.)1
= 3.8 ohm1
(iii)charge = current x time or = 0.4 x 20 (e.c.f.)1
= 8 C1
5 (max)
(b)(i)two lengths in parallel 1
correctly shown on Fig. 8.2 1
(ii)two lengths in series 1
correctly shown on Fig. 8.3 1
3 (max)
(c)energy = l x l x R x t or V x l x t1
= 0.6 x 0.6 x 5 x 201
= 36 J1
3
9(a)(i)any method of induction1
any mention of magnetic field 1
changing / alternating 1
core transmits (changing) magnetic field from primary to secondary1
(ii)no change in magnetic field1
energy not transferred from primary to secondary1
5 (max)
(b)(i)voltage ratio = turns ratio 1
2000 turns on primary 1
(ii)primary voltage x primary current = sec voltage x sec current 1
0.2 A1
4
10(a)each correct entry scores one mark5
(b)(i)mass of nucleus (much) greater than alpha particle1
after collision effect on alpha particle greater1
(ii)positive charge1
repulsion from the positive nucleus1
(iii) most alpha particles pass straight through1
most of atom space or nucleus much smaller than atom1
5 (max)
1