• 9702 November 2010 Paper 22 Worked Solutions | A-Level Physics

Paper 22

Question 1

{Detailed explanations for this question is available as Solution 537 at Physics 9702 Doubts | Help Page 105 - http://physics-ref.blogspot.com/2015/04/physics-9702-doubts-help-page-105.html}

Question 2

{Detailed explanations for this question is available as Solution 370 at Physics 9702 Doubts | Help Page 67 - http://physics-ref.blogspot.com/2015/02/physics-9702-doubts-help-page-67.html}

Question 3

(a)

The centre of gravity of a body is the point at which the (whole) weight (of the body) appears / seems to act.

(b)

Uniform rectangular sheet of card if weight W suspended from wooden rod. Card held to one side as shown.

(i)

C - position of centre of gravity of card:

Point C is shown at the centre of the rectangle

(ii)

W – weight of card:

The arrow is vertically downwards, from point C

(c)

Card in (b) released. Card swings on rod and eventually comes to rest.

(i)

2 forces, other than its weight and air resistance, that act on card during the time that it is swinging. State where forces act:

The reaction / upwards / supporting / normal reaction force and the force of friction. The force(s) act at the rod.

(ii)

By reference to completed diagram of Fig, state + explain position in which card comes to rest:

The card comes to rest with (the line of action of) the weight acting through the rod so that the weight does not have a moment about the pivot / rod.

Question 4

{Detailed explanations for this question is available as Solution 652 at Physics 9702 Doubts | Help Page 130 - http://physics-ref.blogspot.com/2015/05/physics-9702-doubts-help-page-130.html}

Question 5

Student studying water wave in which all wavefronts are parallel to one another. Variation with time t of displacement x of a particular particle in wave shown.

Distance d of oscillating particles from source of waves is measured. At a particular time, variation of displacement x with this distance d shown.

(a)

Define, for a wave:

(i)

The displacement of a wave is the distance (of a point on the wave) from the rest / equilibrium position.

(ii)

Wavelength is the distance moved by wave energy / wavefront during one cycle of the source

OR the minimum distance between 2 points with the same phase

OR minimum distance between adjacent crests or troughs

(b)

Use Figs to determine, for water wave,

(i)

Period T of vibration:

T = 0.60s

(ii)

Wavelength λ:

λ = 4.0cm

(iii)

Speed v:

v = λT              or         v = f λ and      f = 1/T

v = 6.7cms^-1

(c)

(i)

Explain whether wave is losing power as it moves away from source:

The amplitude is decreasing, so the wave is losing power.

(ii)

Ratio of intensity of wave at source to intensity of wave 6.0cm from source:

Intensity, I ∝ (Amplitude, A)²

At source, A = 2.0 and at distance = 6.0cm, A = 1.1

Ratio = 2.0² / 1.1² = 3.3

Question 6

{Detailed explanations for this question is available as Solution 501 at Physics 9702 Doubts | Help Page 97 - http://physics-ref.blogspot.com/2015/03/physics-9702-doubts-help-page-97.html}

Question 7

Results of alpha-particle scattering experiment provided evidence for existence and small size of nucleus.

(a)

Result that provided evidence for

(i)

Small size of nucleus, compared with the atom:

Most α-particles were deviated through small angles

(ii)

Nucleus being charged and containing majority of mass of atom:

A small fraction of the α-particles were deviated through large angles greater than 90^o

(b)

Alpha-particle in this experiment originated from decay of a radioactive nuclide. 2 reasons why beta-particles from radioactive source would be inappropriate for this type of scattering experiment:

Any 2 sensible suggestions:

e.g. β-particles have a range of energies

β-particles are deviated by (orbital) electrons

β-particle has a (very) small mass