Suggested Answers to 2014 A Level H2 Physics 9646 PAPER 3

H2 PHYSICS PRACTICAL (20% weightage)

1 ai) The horizontal component of the velocity is unchanged.

ii) Along the vertical direction, the object’s velocity increases linearly from zero. This is because a resultant downward force acts on the object to cause it to accelerate. Thus velocity increases with t by the relationship of v(y) = gt.

bi) Horizontal component of the velocity decreases with time due to air resistance acting opposite to the object’s direction of motion.

ii) Vertical component of the object’s velocity increases from 0 with time at a slower rate due to air resistance. Thus the downward acceleration is less than g.

c) Path with air resistance will fall closer to the building.

2 ai) The angle which is subtended at the centre of a circle by an arc length equal to the radius of the circle.

ii) The product of 2π radian and the frequency.

bi) Ek = 0 , Ep = mgh = 4.7 x 10^-3 J

ii) 0.557 Hz

3 a) Increase in internal energy of a system is the sum of work done on the system and the heat supplied to the system.

bi) 4.98 x 10^-2 mol

ii) 1. -226 J

2. 0 J

iii) work done on gas: -226 , heat supplied to gas: -884

increase in internal energy: 344, 540, -884

4 a) Resultant displacement at a point due to two or more waves is the vector sum of the displacements due to those waves acting individually.

bi) 57.3º

ii) 0.49 : 1

5 a) Emax = h (c/f) – hf

bi) 4.35 x 10^-7

ii) Gradient of graph = hc

h = 6.667 x 10^34 J

c) Draw a line parallel to the original line but cutting the x-axis at a larger value.

6 a) A region of space set up by a mass, a charged particle or magnet, and surrounding the body, a field which can exert a force on another body that is not physical.

ii) The statement did not specify the type of field and state of particle. Hence the field may be gravitational field, and the force is due to the mass of the particle. The field may also be magnetic field. The magnetic force on the particle is only zero when it is in motion and not moving parallel to the magnetic field.

bi) Any point within a charged sphere will have no electric field.

ii) 1. A = 4.0cm B = 2.0cm

2. The spheres have opposite signs. Since E is always >0, indicating that the electric fields from A and B are in the same direction.

iii) 1. 3.00 x 10^-15 J

2. a= 1.24 x 10^13 m/s²

3. From 4 to 18.5 cm, the electric field is predomniantly contributed by sphere A and decreasing with distance from A. Acceleration is +3eE/m

The acceleration of the nucleus decreases from a max value at 4cm to a minimum value at 18.5cm

From 18.5 to 28 cm, the minimum E starts to increase again, indicating that the E-field from 18.5cm onwards is predominantly from B. The E field’s direction is the same, and E >0, the lithium nucleus acceleration increases again.

7 ai) The ratio of the potential difference across the wire to the current flowing through the wire.

ii) The resistivity of a wire is a property of the material. It is related to the resistance by the equation R = pl/A

bi) 4.9Ω

ii) 118 turns

c) B = 0.72μ (NI/r)

di) 8.54 x 10^-24

ii) 4.58 x 10^-2

e) Vertical component of the electron’s velocity is perpendicular to the B field and hence it is subjected to a centripetal force. Horizontal component is parallel to the B field and remains constant as there is no magnetic force accelerating the horizontal velocity. Hence the resultant path is helical.

8 ai) A spontaneous and random process in which an unstable nucleus changes into a different nuclide, emitting radiation.

ii) It is unpredictable in both when and which particular nuclide will decay.

iii) Not triggered by external factors.

bi) 2.54 x 10^-10

ii) 4.25kg

ci) 156 W

di) The half life of plutonium is much longer than polonium. For a space flight lasting several years, the original quantity of polonium will have decayed to less than half in a year. Since plutonium has a long half life, over seven years, more than half would still be remaining.

ii) Plutonium has a higher power density as strontium has a much smaller mass and energy release.

A -LEVEL H2 MATH JUNE HOLIDAYS INTENSIVE REVISION

A-LEVEL H2 PHYSICS JUNE HOLIDAYS INTENSIVE REVISION