Edexcel GCE Physcis 2008 Unit 4 mock exam 15_16 with mark scheme

8/18/2019 Edexcel GCE Physcis 2008 Unit 4 mock exam 15_16 with mark scheme

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SECTION A

Answer ALL questions.

For questions 1–10, in Section A, select one answer from A to D and put a cross in the box .

If you change your mind, put a line through the box and then

mark your new answer with a cross .

1. A current-carrying wire is placed into a magnetic field. If the magnetic force experienced by the wirebalances the weight of the wire, the wire will float.

The direction of the magnetic field is from west to east.

For the wire to float, it is placed

A parallel to the magnetic field so the current flows from east to west.

B parallel to the magnetic field so the current flows from west to east.

C perpendicular to the magnetic field so the current flows from north to south.

D perpendicular to the magnetic field so the current flows from south to north.

(Total for question = 1 mark)

2. A particle Z has kinetic energy E and momentum p. A second particle X has twice the mass and half themomentum of particle Z .

The kinetic energy of X is

A 2E

B E/4

C E/8

D E/16(Total for question = 1 mark)

3. Two capacitors of capacitance 1000 µF and 10 µF are charged so that they store the same amount ofenergy. The potential difference (p.d.) across the 1000 µF capacitor is V 1 and the p.d. across the 10 µFcapacitor is V 2.

The value of is

A 1 × 10−4

B 1 × 10−2

C 1 × 102

D 1 × 104



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4. Select the row of the table that correctly identifies what happens in an elastic collision.


5. A particle moving in a circular path completes 7.5 revolutions in 9.0 s.Its angular velocity in rad s−1 is

A 0.83

B 5.2

C 68

D 420


6. The diagram shows the path of an α particle that is being deflected by the nucleus of an atom. The pointP on the path is the point of closest approach of the α particle to the nucleus.

Which statement about the α particle on this path is correct?

A Its acceleration is least at P.

B Its speed is least at P.

C Its total energy is greatest at P.

D Its momentum is greatest at P.



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7. A capacitor is charged to a potential difference of 12 V and stores a charge of 600 µC. What would thepotential difference across the plates have to be in order for the capacitor to store 50% more charge?

A 3 V

B 9 V

C 18 V

D 24 V


8. Which of the following is not a unit of electric field strength?

A J C m−1

B J C−1 m−1

C N A−1 s−1

D N C−1


9. A cyclist travels along a straight horizontal road at a steady speed. A net force of 20 N is then applied for6 s. The change in momentum of the cyclist is

A 3.3 kg m s−1

B 26 kg m s−1

C 120 kg m s−1

D 720 kg m s−1


10. The mass in MeV/c 2 of a 1.8 × 10-29 kg positron is

A 10B 3.2 × 10-59

C 3.3 × 10-8

D 1.0 × 107

(Total for Question = 1 mark)

TOTAL FOR SECTION A = 10 MARKS


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SECTION B

Answer ALL questions in the spaces provided.

11. The diagram shows a simple generator. It has a flat coil of negligible resistance which can be rotated ina magnetic field. The coil has 500 turns and an area of 2.5 × 10−3 m2.

The graph shows the variation of the magnetic flux linkage NΦ with time t as the coil is rotated at asteady frequency in a uniform magnetic field.

(a) Determine the frequency of rotation of the coil. (2)

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Frequency = ...........................................................


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(b) Determine the magnetic flux density of the field. (2)

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Magnetic flux density = ...........................................................

(c) Determine the maximum e.m.f. induced in the coil. (3)

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Maximum e.m.f. = ...........................................................

(Total for question = 7 marks)

12. A student was investigating the charge and discharge of a capacitor.

He set up the following circuit.

(a) Calculate the time constant for the circuit. (2)

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Time constant = ...........................................................


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(b) The student wanted to plot a current-time graph as the capacitor charged, but found that thecurrent changed too rapidly for him to take readings.

Instead, he modelled the experiment using a spreadsheet. The switch was closed at time t = 0 s. V is the potential difference across the capacitor.

Explain how the value in cell B5 is calculated. (2)

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(c) Some of the data from the spreadsheet has been plotted on a graph of current I against time t .

(i) Plot the missing points and draw a line of best fit. (2)(ii) Use the graph to determine a second value for the time constant. (2)

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Time constant = ...........................................................

(iii) Suggest how the student might change his spreadsheet to give a more accurate model of thecharging of the capacitor. (1)

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*(d) An alternative method of determining the time constant is to use a straight line graph.

State and explain the variables that the student should plot and how he should determine the timeconstant from this graph. (3)

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13. The table gives the quark structure of three particles.

The up quark has a charge of +2/3e and the down quark has a charge of −1/3e.

(a) Show that udd is a possible combination of quarks for the neutron. (1)

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(b) State, in terms of quark structure, why the ∆− is classed as a baryon and the π − a meson. (2)

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(c) Another particle in the delta family, the ∆++, is also composed of up and/or down quarks.Its decay is shown by

∆++ → p + π

Deduce the quark content of the ∆++ and the charge on the pion. (2)

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Quark content of ∆++...........................................................

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Charge on pion ...........................................................



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14. In order to make an object move around a circular path at a constant speed a resultant force must act onit.

(a) Explain why a resultant force is required and state the direction of this force. (2)

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(b) When vehicles move around a bend on a level road, the resultant force is provided by frictionbetween the tyres and the road. For a given vehicle and road surface there is a maximum valuefor this sideways frictional force.

Explain why roads designed for high-speed travel, such as motorways, do not have any sharp

bends. (2)

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(c) Some cycling tracks are banked. When cornering, a cyclist moves up the track until the sidewaysfrictional force is zero.

The free-body force diagram for a cyclist and bicycle is shown. The normal contact force exertedby the track is N and the weight of cyclist and bicycle is mg .

(i) By considering the vertical and horizontal motion, show that

tan θ = gr /v 2

where r is the radius of the cyclist's path and v is the cyclist's speed. (3)

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(ii) Calculate the value of θ for a cyclist travelling at 11.0 m s−1 around a bend of radius 18.7 m.(2)

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θ = ...........................................................

(Total for Question = 9 marks)


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15. (a) Explain what is meant by the principle of conservation of momentum. (2)

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(b) The picture shows a toy car initially at rest with a piece of modelling clay attached to it.

A student carries out an experiment to find the speed of a pellet fired from an air rifle. The pellet isfired horizontally into the modelling clay. The pellet remains in the modelling clay as the car movesforward. The motion of the car is filmed for analysis.

The car travels a distance of 69 cm before coming to rest after a time of 1.3 s.

(i) Show that the speed of the car immediately after being struck by the pellet was about 1 m s−1.(2)

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(ii) State an assumption you made in order to apply the equation you used. (1)

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(iii) Show that the speed of the pellet just before it collides with the car is about 120 m s−1

mass of car and modelling clay = 97.31gmass of pellet = 0.84 g (3)

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(c) The modelling clay is removed and is replaced by a metal plate of the same mass. The metalplate is fixed to the back of the car. The experiment is repeated but this time the pellet bouncesbackwards.

*(i) Explain why the speed of the toy car will now be greater than in the original experiment. (3)

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(ii) The film of this experiment shows that the pellet bounces back at an angle of 72° to thehorizontal.

Explain why the car would move even faster if the pellet bounced directly backwards at the

same speed. (1)

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(d) The student tests the result of the first experiment by firing a pellet into a pendulum with a bobmade of modelling clay. She calculates the energy transferred.

The student's data and calculations are shown:

Data

mass of pellet = 0.84 gmass of pendulum and pellet = 71.6 gchange in vertical height of pendulum = 22.6 cm

Calculations

change in gravitational potential energy of pendulum and pellet = 71.6 × 10−3 kg × 9.81 N kg−1 × 0.226 m = 0.16 Jtherefore kinetic energy of pendulum and pellet immediately after collision = 0.16 Jtherefore kinetic energy of pellet immediately before collision = 0.16 Jtherefore speed of pellet before collision = 19.5 m s−1

There are no mathematical errors but her answer for the speed is too small.

State and explain which of the statements in the calculations are correct and which are not. (4)

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16. (a) Fig. 16.1 shows a negatively charged metal sphere close to a positively charged metal plate.

On Fig. 1.1, draw a minimum of five field lines to show the electric field pattern between theplate and the sphere. (2)

(b) Fig. 1.2 shows two positively charged particles A and B.

At point X, the magnitude of the resultant electric field strength due to the particles A and B is zero.

(i) State, with a reason, which of the two particles has a charge of greater magnitude. (1)

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(ii) On Fig. 1.3 sketch the variation of the resultant electric field strength E with distance d from theparticle A. (3)


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(c)The plate in Fig. 1.1 is now earthed. Fig. 1.4 shows the sphere and plate the instant the plate isearthed.

On Fig. 1.4, draw a minimum of five field lines to show the electric field pattern between theplate and the sphere will change if at all. (1)


17. Fig. 17.1 shows the circular path described by a helium nucleus in a region of uniform magneticfield in a vacuum.

Fig. 17.1

The direction of the magnetic field is perpendicular to the plane of the paper. The magnetic flux densityof the magnetic field is 0.20 mT. The radius of the circular path is 15 cm. The helium nucleus has charge+ 3.2 × 10 –19 C and mass 6.6 × 10 –27 kg.

(a) Explain why the helium nucleus

(i) travels in a circular path (1)

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(ii) has the same kinetic energy at A and B. (1)

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Fig. 1.4


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(b) Calculate the magnitude of the momentum of the helium nucleus. (3)

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momentum = ............................................ kgms –1

(c) Calculate the kinetic energy of the helium nucleus. (2)

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kinetic energy = ....................................................... J

(d) A uniform electric field is now also applied in the region shaded in Fig. 2.1. The direction of thiselectric field is from left to right. Describe the path now followed by the helium nucleus in the electricand magnetic fields. (2)

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18. An electron and a positron annihilate with the emission of two photons of equal energy.Calculate the wavelength of the photons. (5)

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Wavelength = ...........................................................(Total for question = 5 marks)

TOTAL FOR SECTION B = 70 MARKS

TOTAL FOR PAPER = 80 MARKS


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List of data, formulae and relationships

Acceleration of free fall g = 9.81 m s-2 (close to Earth’s surface)

Boltzmann constant k = 1.38 x 10-23 J K -1

Coulomb’s law constant k = 1/4πε

= 8.99 x 109 N m2 C-2

Electron charge e = -1.60 x 10-19 C

Electron mass m = 9.11 x 10-31 kg

E1ectronvo1t 1 eV = 1.60 x 10-19 J

Gravitational constant G = 6.67 x 10-11 N m2 kg-2

Gravitational field strength g = 9.81 N kg-1 (close to Earth’s surface)

Permittivity of free space ε = 8.85 x 10-12 F m-1

Planck constant h = 6.63 x 10-34 J s

Proton mass m = 1.67 x 10-27 kg

Speed of light in a vacuum c = 3.00 x 108

m s-1

Stefan-Bo1tzmann constant σ = 5.67 x 10-8 W m-2 K -

Unified atomic mass unit u = 1.66 x 10-27 kg

Unit 1

Mechanics

Kinematic equations of motion v = u + at

s = ut + ½at 2

v2 = u2 + 2as

Forces Σ F = ma g = F/m

W = mg

Work and energy ΔW = F Δ s

= ½mv2

Δ E grav

= mg Δh

Materials

Stokes’ law F = 6πηrv

Hooke’s law F = k Δ x

Density ρ = m/V

Pressure p = F/A

Young modulus E = σ / ε where

Stress σ = F/A

Strain ε =Δ x/x

Elastic strain energy E el

= ½ F Δ x


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20

1 2 1 2

1 2 3

max

Unit 2

Waves

Wave speed v = f λ

Refractive index µ = sin i/ sin r = v /v

Electricity

Potential difference V = W/Q

Resistance R = V/I

Electrical power, energy and P = VI

efficiency P = I 2 R

P = V 2/ R

W = VIt

% efficiency =useful energy output

total energy inputx 100

% efficiency =useful power output

total power inputx 100

Resistivity R = ρl/A

Current I =ΔQ/ Δt

I = nqvA

Resistors in series R = R + R + R

Resistors in parallel

Quantum physics

Photon model E = hf

Einstein’s photoelectric hf = o / + ½mv2

equation

Turn over


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Unit 4

Mechanics

Momentum p = mv

Kinetic energy of a

non-relativistic particle E = p

2

/2mMotion in a circle v = ωr

T = 2π/ω

F = ma = mv2/r

a = v2/r

a = r ω2

Fields

Coulomb’s law F = kQ Q /r 2 where k = 4πε0

Electric field E = F/Q

E = kQ/r 2

E = V/d

Capacitance C = Q/V

Energy stored in capacitor W = ½QV

Capacitor discharge Q = Q e-t/RC

In a magnetic field F = BIl sin θ

F = Bqv sin θ

r = p/BQ

Faraday's and Lenz's Laws ε = -d( No / )/dt

Particle physics

Mass-energy Δ E=c2Δm

de Broglie wavelength λ = h/p


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BLANK PAGE


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Mark Scheme

Section A

Question

Number

Answer Mark

1 C

2 C

3 B

4 A

5 B

6 B

7 C

8 A

9 C

10 A

Section B

Q11.


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Q12.


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Q13.

Q14.


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Q15.


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Q16.


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Q17.

Q18.

Edexcel GCE Physcis 2008 Unit 4 mock exam 15_16 with mark scheme

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