Hints offered by J Spence

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Section 1

Question 1

Hint 1: Acceleration is the gradient of a velocity time graph

Hint 2: Substitute values from graph into a = (v-u)/t to find acceleration

Question 2

Hint 1: Find the unbalanced force on the block horizontally using F = ma

Hint 2: Find the horizontal component of 24 N force using F horizontal = F cos(θ)

Hint 3: The unbalanced force F (found in hint 1) = forward horizontal force - opposing friction force

Question 3

Hint 1: When the line on a speed time graph is horizontal, the object is moving at a constant speed.

Hint 2: For a skydiver to decelerate while travelling downward, there must be an unbalanced force upward.

Hint 3: When the forces acting on an object are balanced, F = 0 and there is no acceleration.

Question 4

Hint 1: The length of an object at rest relative to an observer is called the rest length, l.

Hint 2: The length of an object moving relative to an observer is called the contracted length l'

Hint 3: Contracted lengths can be determined using the formula l' = l√(1-(v/c)²)

Question 5

Hint 1: Use the formula v = H_{0}d

Question 6

Hint 1: know that evidence supporting the existence of dark energy comes from the accelerating rate of expansion of the Universe.

Question 7

Hint 1: know that the temperature of stellar objects is related to the distribution of emitted radiation over a wide range of wavelengths

Hint 2: know that the peak wavelength of this distribution is shorter for hotter objects than for cooler objects.

Hint 3: know that hotter objects emit more radiation per unit surface area per unit time than cooler objects.

Question 8

Hint 1: know that nuclear equations can describe radioactive decay

Hint 2: know that the upper number of the symbol of an element is the mass number

Hint 3: know that the lower number of the symbol of an element is the atomic number

Hint 4: know that the mass numbers on the right hand side of the equation should add to give the mass number on the left hand side

Hint 5: know that the atomic numbers on the right hand side of the equation should add to give the atomic number on the left hand side

Hint 6: use the periodic table at the front of the paper to check the element with the corresponding atomic number

Question 9

Hint 1: what affect will the new radiation's higher freqency have on the photon's energy?

Hint 2: given an increase in the energy of the incident photons, how will the
kinetic energy of the emitted electrons change (E_{k} = energy of photon - work function)

Hint 3: Irradiance = P/A. Power is Energy per second incident on the plate.

Hint 4: If energy of incident photons has increased, and irradiance has stayed constant, then the number of photons hitting the plate has decreased.

Question 10

Hint 1: determine the energy of the photon using E = hf

Hint 2: using E_{k} = hf− hf_{0}, find hf_{0} (the work
function), using the value of E_{k} is given in the question

Question 11

Hint 1: know that coherent waves have a constant phase relationship, and have the same frequency, wavelength and speed

Question 12

Hint 1: be aware that a change in refractive index results in a change of speed and wavelength as light passes from one medium to another

Question 13

Hint 1: know that angles of incidence and refraction are measured between the normal and the ray

Hint 2: know that light travels at 3×10^{8} m/s in air

Hint 3: use n = sin(θ_{1}) / sin(θ_{2}) =
v_{1}/v_{2} to solve for v_{2}

Question 14

Hint 1: know that systematic errors can be identified when a line graph has a y-intercept that is non-zero

Hint 2: be aware that when 1/d² was small (ie near 0), d would be a large distance away from the small lamp

Hint 3: according to the graph, when d was large, there is a non-zero irradiance. This indicates there were external light sources affecting the experiment.

Question 15

Hint 1: use the formula I₁d₁² = I₂d₂², where the question gives you d₁, I₁ and d₂.

Question 16

Hint 1: the peak voltage is measured using the vertical distance from the middle of the wave to the top of the wave

Hint 2: the Y-gain tells you the scale for the vertical axis. In this case, each division is worth 1.0V

Hint 3: determine the peak voltage by multiplying the number of divisions from the middle to the top of the wave by the Y-gain

Hint 4: use V_{rms} = V_{peak}/ √2 to determine
V_{rms}

Question 17

Hint 1: the charge stored in a capacitor is given by the formula Q = CV. C is the capacitance and V is the voltage across the capacitor when it is fully charged.

Question 18

Hint 1: the two resistors act as a potential divider for the 6 V supply. The voltage across the capacitor is equal to

Hint 2: The voltage across components in parallel are equal (hence the voltage across the capacitor is equal to the voltage across the 120Ω resistor

Hint 3: determine the voltage across the 120Ω resistor using V₂ =
(R₂/(R₁+R₂)) x V_{s}

Hint 4: use E = ½CV² to determine energy stored in capacitor, where C is capacitance and V is voltage across capacitor

Hint 5: remember 30 μF = 30 × 10^{-6} F

Question 19

Hint 1: know that for conductors we have the situation where one or more bands are partially filled.

Hint 2: know that some metals have free electrons and partially filled valence bands, therefore they are highly conductive

Hint 3: know that some metals have overlapping valence and conduction bands. Each band is partially filled and therefore they are conductive

Hint 4: know that in an insulator, the highest occupied band (called the valence band) is full. The first unfilled band above the valence band is the conduction band. For an insulator, the gap between the valence band and the conduction band is large and at room temperature there is not enough energy available to move electrons from the valence band into the conduction band where they would be able to contribute to conduction.

Hint 5: know that in a semiconductor an increase in temperature increases the conductivity of a semiconductor.

Question 20

Hint 1: given that F and l are given in the question, use the formula to determine d²

Hint 2: don't forget to square root d² to find d

Section 2

Question 1

1a)i) Hint 1: know that acceleration is the rate of change of velocity

1a)i) Hint 2: the rate of change of velocity is how much the velocity changes in one second

1a)i) Hint 3: when given a value of acceleration, that value must be used in explaining how much the velocity is changing in one second.

1a)ii) Hint 4: write suvat down the left hand side of the page and identify which values are given in the question

1a)ii) Hint 5: the suvat values are s = ?, u = 0, v = ?, a = 0.32m/s², t = 25s

1a)ii) Hint 6: use s = ut + ½at² to determine the distance travelled

1b)i) Hint 7: know that the frequency of the train (the source frequency,
f_{s}) is 270 Hz and the observed frequency (f_{o}) is 290 Hz

1b)i) Hint 8: use the formula f_{o} = f_{s}
(v/(v±v_{s})), where v_{s} is the speed of the train and v is the speed of sound, to
find v_{s}.

1b)i) Hint 9: remember since the train is moving toward the observer, the
bottom line of the equation should be v - v_{s}

1b)ii) Hint 10: know that the frequency of a sound relates to the number of waves (or wavefronts) passing a point in a second)

1b)ii) Hint 11: if the frequency observed is lower, what happens to the number of wavefronts observed per second?

1b)ii) Hint 12: what would a diagram look like of the wavefronts if the source was moving away from an observer (think about the distance between wavefronts)

Question 2

2a)i) Hint 1: apply the law of conservation of linear momentum (total momentum before = total momentum after)

2a)i) Hint 2: use the formula m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

2a)i) Hint 3: remember that the balls are moving in different directions.

2a)i) Hint 4: If the white ball is moving to the right, its direction is positive. The black balls direction will therefore be negative.

2a)i) Hint 5: include the direction of the white ball in your final answer (include the sign)

2a)ii) Hint 6: know that an inelastic collision is one where kinetic energy is lost

2a)ii) Hint 7: it is not sufficient to say kinetic energy is not conserved, you must state how it has changed.

2b)i) Hint 8: recognise that the formula Ft = mv - mu can be used.

2b)i) Hint 9: the initial velocity, final velocity and time of contact are given in the question

2b)ii) Hint 10: the percentage uncertain in a calculated value is equal to the largest percentage uncertainty in any of the values used to calculate it

2b)ii) Hint 11: determine the percentage uncertainty in each of the quantities mass, speed and time

2b)ii) Hint 12: percentage uncertainty can be calculated by the formula (Δy/y) × 100, where Δy is the value of the absolute uncertainty

Question 3

3a)i) Hint 1: write suvat down the left hand side of the page and identify which values are given in the question

3a)i) Hint 2: you should have u = 5.6 ms^{-1}, v = 0, a = -9.8
ms^{-2} and t = ? (remember, at max height v = 0)

3a)i) Hint 3: use v = u + at to solve for t

3a)ii) Hint 4: write suvat down the left hand side of the page and identify which values are given in the question

3a)ii) Hint 5: you should have u = 0 ms^{-1}, v = -7.7
ms^{-1}, a = -9.8 ms^{-2} and s = ? (or down is positive direction and v and a are both
positive)

3a)ii) Hint 6: use v² = u² + 2as to solve for s

3b) Hint 7: know that acceleration is the same, so gradient of line drawn will be equal to original line

3b) Hint 8: initial vertical velocity starts higher, so what affect will that have on time to reach max height (when v = 0)?

3b) Hint 9: max height is greater, so what affect will that have on speed of ball when it hits the ground?

Question 4

Hint 1: remember, open ended question is there to show off your knowledge of Physics, so you must apply Higher Physics knowledge to the context

Hint 2: an answer does not have to be perfect, or complete, for 3 marks, but simply display a good knowledge of Physics

Hint 3: think about how this situation relates to the formula provided

Hint 4: identify that the freqency relates to the number of cars passing a point in one second

Hint 5: identify that the wavelength in the formula relates to the distance from one car to the next

Hint 6: consider how low frequency and wavelength relate to congestion and the speed of vehicles (perhaps with example calculations)

Hint 7: consider how high frequency and wavelength relate to congestion and the speed of vehicles (perhaps with example calculations)

Hint 8: consider showing how the units for speed compare with the units of frequency × wavelength

Hint 9: relate the idea that a wave model is essentially being use to describe objects that appear like particles, where else in Physics does this occur?

Question 5

5a)i) Hint 1: a calculation showing the ratio of the mass of the star to the mass of the planet is required

5a)i) Hint 2: the calculation can be simplified to simply compare the powers of ten

5a)i) Hint 3: understand that one power of ten increase is equivalent to an order of magnitude increase

5a)i) Hint 4: determine how many powers of ten bigger is the star to the planet

5a)ii) Hint 5: the two masses and the distance between the bodies is given in the question

5a)ii) Hint 6: use F = GM₁m₂/r² to determine the gravitational force between the bodies

5a)ii) Hint 7: G is the universal gravitational constant, given in the data sheet at the front of the exam paper

5b)i) Hint 8: know that redshift is the ratio of the speed of the star to the speed of light (z = v/c)

5b)i) Hint 9: use the recession speed given for the star and the speed of light to calculate redshift

5b)ii) Hint 10: how would the force on the star be affected by the mass of the larger planet

5b)ii) Hint 11: assuming the force on the star is larger due to a planet of larger mass, what impact would that have on the star's radius of orbit?

Question 6

6a) Hint 1: use E = hf to determine how a high frequency photon would affect the energy of the photon

6a) Hint 2: recognise that when photons are absorbed by electrons, the electrons jump up to higher energy levels.

6a) Hint 3: an absorption of the highest frequency photon would correspond to the highest energy transition

6a) Hint 4: the direction of the transition is upward, this must be included in your response

6b) Hint 5: find the energy difference between E₁ and E₃ by calculating E₃ - E₁

6b) Hint 6: recognise that this energy difference corresponds to the energy of photon absorbed

6b) Hint 7: Use E = hf to determine the frequency of the photon absorbed, given planck's constant on the data sheet

Question 7

7a) Hint 1: understand that fundamental particles are particles that cannot be broken down into smaller particles

7b)i) Hint 2: recognise that hadrons is the term given to any composite particle made of quarks, either 2 quarks (quark and anit-quark pair called a meson) or 3 quarks (baryon)

7b)i) Hint 3: recognise that baryons are composite particles made of 3 quarks

7b)ii) Hint 4: notice in the table that the sigma plus particle has a charge of +1

7b)ii) Hint 5: notice that the sigma plus particle has two up quarks and one strange quark

7b)ii) Hint 6: determine the total charge of 2 up quarks

7b)ii) Hint 7: subtract the total charge of the 2 up quarks from the total charge of the sigma plus to determine the charge of the strange particle

7c)i) Hint 8: know that the strong force holds quarks together in a nucleus

7c)ii) Hint 9: know that the gluon is the force carrier (boson) associated with the strong force

7d) Hint 10: note that the mean lifetime of the sigma minus particle in their frame of reference is a proper time t

7d) Hint 11: note that the mean lifetime of the sigma minus particle in an observers (who is moving relative to them) frame of reference is the dilated time t'

7d) Hint 12: dilated times can be determined using the formula t' = t / √(1-(v/c)²

7d) Hint 13: the value of the speed of the particle v can be
determined as 0.9 × the speed of light, 3 × 10^{8} ms^{-1}

Question 8

8a)i) Hint 1: find the charge of the electron on the data sheet

8a)i) Hint 2: use the formula W = QV to determine the work done W in accelerating the electron of charge Q through the potential V

8a)ii) Hint 3: recognise that the particle must always accelerate forward (from left to right)

8a)ii) Hint 4: for the particle to accelerate forward the force must always be forward (from left to right)

8a)ii) Hint 5: for the force to always be forward the electric field must always be in the same direction, why does this mean an alternating supply is necessary?

8b)i) Hint 6: use right hand rule for electron flow. First finger field, second finger current, thumb force.

8b)i) Hint 7: align 2nd finger with electron direction, thumb with force direction (up), which direction is first finger pointing?

8b)ii) Hint 8: electron beam is being forced in opposite direction, what change to magnetic field would cause this

8b)ii) Hint 9: electron beam curvature is greater, indicating a greater force on it. What change to magnetic field would cause this?

8c) Hint 10: assume that the kinetic energy of the electron equals the energy of the photon

8c) Hint 11: use E_{k} = ½mv², where Ek is equal to
the energy of photon produced, and m is the mass of the electron (found in the data sheet)

Question 9

9a) Hint 1: know that nuclear fusion is the combining of two small nuclei to form a larger nucleus

9a) Hint 2: alternatives for nuclei, for example, atom, molecule, particle, isotope or element are not acceptable.

9b)i) Hint 3: know that mass is lost in a nuclear fusion reaction

9b)i) Hint 4: what does Einstein's equation E = mc² tell us about the mass lost in a nuclear reaction?

9b)ii) Hint 5: using the masses given in the table, determine the mass lost in the reaction by subtracting the total mass after from the total mass before the reaction

9b)ii) Hint 6: use E = mc² to determine the energy released in the reaction. c is the speed of light.

Question 10

10a) Hint 1: know that a maximum is an region where constructive interference of the two waves has occurred.

10a) Hint 2: know that for constructive interference to occur, waves must meet in phase

10a) Hint 3: waves meeting in phase can be explained in various ways, eg, crest meets …….?, trough meets ……..?

10b)i) Hint 4: the graph is a straight line that passes through the origin. This can be represented mathematically by y = mx

10b)i) Hint 5: apply the formula y = mx to mλ = dsin(θ) to determine what the gradient of the line represents

10b)i) Hint 6: since the y-axis is sin(θ) and the x-axis is 1/d, the gradient of the line must be equal to λ

10b)i) Hint 7: use m = (y₂-y₁)/(x₂-x₁) to determine the gradient (you must take points from the line rather that use the data points)

10b)i) Hint 8: state the value of the gradient as equal to the wavelength with the correct units.

10b)ii) Hint 9: Method 1 using best fit line. Determine 1/d from value of d given

10b)ii) Hint 10: 1/d = 0.5 × 10^{6}. Use value to determine
value of sin(θ) from best fit line

10b)ii) Hint 11: determine θ based on the value of sin(θ) found it graph

10b)ii) Hint 12: Method 2:use mλ=dsin(θ), with value of λ from part 10(b)(i) and d value in question to determine sinsin(θ). Note that m = 1.

10c) Hint 13: be aware that reliablility relates to how close repeated measurements are to each other.

10c) Hint 14: experiments are proven reliable if the measurements are repeated and the same values are given over and over again.

10c) Hint 15: reliability of measurements are improve through the design of the experiment. How can the design be improved?

10c) Hint 16: the measurements can be taken more reliably if the maximum are further apart. How can this be achieved?

10c) Hint 17: what affect will moving the screen have of the separation of maxima?

10c) Hint 18: what affect will using a second order maxima have on the measurement of θ?

10c) Hint 19: what affect will measuring from a first order maxima to the first order maxima on the other side of the central maxima have on the measurement of θ?

10c) Hint 20: would using additional gratings of the same size improve reliability?

Question 11

Hint 1: this analogy is similar to the soldier analogy for understanding refraction.

Hint 2: consider that refraction relates to the ratio of the speed of light in a medium to the speed of light in a vacuum

Hint 3: when the car wheel enters the sand, it is analogous to light entering a dense medium from a vacuum or the air

Hint 4: how does the traction of the wheel on sand compare to the road surface?

Hint 5: if the front tyre on the road can grip better than the front tyre on sand, how will this affect the motion of the car.

Hint 6: recognise that the front wheel in the sand will not travel as far as the front wheel on the road (ie, it is travelling slower in the sand)

Hint 7: recognise that this change of speed in the sand results in a change of direction of the vehicle

Hint 8: this change of direction is analogous to a wavefront of light incident on a glass surface from air at an angle to the normal.

Question 12

12a) Hint 1: know that the emf of a cell is a measure of the energy supplied to each coulomb of charge passing through the cell

12a) Hint 2: when the question states a value of emf the answer must be stated in terms of the value of energy given to each coulomb of charge passing through the cell.

12b)i) Hint 3: this is a SHOW THAT question, therefore a formula must be stated at the start

12b)i) Hint 4: know that the lost volts can be determined by using the formula lost volts = Ir (that is, current drawn from supply × internal resistance)

12b)i) Hint 5: recognise that the current is given in the question in mA and must be converted to amps (A).

12b)i) Hint 6: appreciate that there are two internal resistor values given which must be added together before used in the formula "lost volts = Ir"

12b)ii) Hint 7: know that the reading on the voltmeter is the terminal potential difference (also known as terminal voltage).

12b)ii) Hint 8: know that the terminal voltage is the difference between the emf and the lost volts (that is, V = E - Ir)

12b)ii) Hint 9: know that emf is the total emf of both cells

12b)ii) Hint 10: know that the answer should be given to 2 significant figures

12b)iii) Hint 11: know that the power through the lamp is given by the formula P = IV

12b)iii) Hint 12: recognise that the current is given in the question in mA and must be converted to amps (A).

12b)iii) Hint 13: recognise that the voltage across the lamp is equal to the terminal potential difference determined in 12(b)(ii).

12b)iii) Hint 14: know that power is measured in units of watts (W).

12c) Hint 15: know that the terminal voltage is the difference between the emf and the lost volts (that is, V = E - Ir)

12c) Hint 16: know that emf is the total emf of all 4 cells

12c) Hint 17: know that the total internal resistance is the resistance of all 4 internal resistors added together in series

12c) Hint 18: appreciate that the terminal potential difference is the voltage across both the LED and resistor R

12c) Hint 19: determine the voltage across the resistor by subtracting the voltage across the LED (3.6 V) from the terminal potential difference already calculated

12c) Hint 20: know that the current through the resistor R is equal to the current through the LED (and must be converted to amps)

12c) Hint 21: use R = V/I where V is the voltage across the resistor and I is the current through it

12c) Hint 22: know that resistance is measured in ohms (Ω)

Question 13

13a) Hint 1: know that the initial charging current is determined using I = V/R, where V is the supply voltage and R is the value of the resistance in the circuit.

13a) Hint 2: know that when the switch is open the second resistor is not connected to the circuit.

13a) Hint 3: know that the units of current are amps (A)

13b) Hint 4: recognise that when switch S2 is closed, the second resistor is in parallel with the first.

13b) Hint 5: know that when resistors are connected in parallel the total resistance of the circuit is less.

13b) Hint 6: what happens to the initial charging current in the circuit if the total resistance of the circuit is less?

13b) Hint 7: note that your answer must include the word INITIAL or AVERAGE current is necessary for the mark

Question 14

14a) Hint 1: the name relates to the PHOTONS incident on the junction producing a POTENTIAL DIFFERENCE (or voltage)

14a) Hint 2: know that the effect of photons producing a pd on a pn junction diode is the photoelectric effect.

14b)i) Hint 3: know that the power through the lamp is given by the formula P = IV

14b)i) Hint 4: determine the current through the resistor using the line of the graph where the voltage is 2.1 V

14b)i) Hint 5: note that the current is midway between 30 and 40 mA

14b)i) Hint 6: know that current must be converted into amps (A) before used in the formula P = IV

14b)i) Hint 7: know that the power should be stated to 2 sig fig and the units are watts (W).

14b)ii) Hint 8: answer must convey an understanding of how the number of photons hitting the cell changes

14b)ii) Hint 9: given the power output is changing, answer must explain how the rate of photons hitting the cell changes (i.e., number hitting per second).

Question 15

15a) Hint 1: note that the resistance can be determined using the equation given in the question

15a) Hint 2: note that all values to determine the resistance are given in the question

15a) Hint 3: recognise that since each value is given to 2 sig fig, the answer must have 2 sig fig and have the units for resistance, ohms (Ω)

15b)i) Hint 4: know that a graph of R against L means R is on the y-axis and L is on the axis

15b)i) Hint 5: the scale on each axes should include the full range of data and be linear

15b)i) Hint 6: the labels on each scale should have quantity labels and units
(and the resistance scale must include ×10^{-3})

15b)i) Hint 7: all points must be plotted accurately

15b)i) Hint 8: the best fit line should be straight but does not need to be forced through the origin

15b)ii) Hint 9: the gradient must be determined using two points on the best fit line, not taken from two data points

15b)ii) Hint 10: the gradient can be determined using the equation m = (y₂-y₁)/(x₂-x₁)

15b)ii) Hint 11: the value of gradient is expected to be between 3.7 and
4.0 (×10^{-3})

15b)ii) Hint 12: the unit for the gradient does not need to be stated,
but if it is, it should be correct (Ωm^{-1})

15b)iii) Hint 13: recognise that the formula R = ρL/A can be written in the form y = mx where y = R, x = L and the gradient m = ρ/A

15b)iii) Hint 14: given m = ρ/A, rearrange for ρ to determine a formula that uses the gradient of the line and the Area to find the resistivity of the metal wire

15b)iii) Hint 15: use ρ = m × A, which the gradient found in 15(b)(ii) and the cross sectional area stated in 15(b) to determine the resistivity of the wire

15b)iii) Hint 16: the unit for resistivity must be used, and is stated in part 15(a).

Did this hint help?