Hints offered by I Lawrie

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Section 1

Question 1

Hint 1: Scalar only requires direction

Question 2

Hint 1: Displacement is distance away from start point with direction.

Hint 2: If you start and finish at the same point, displacement has to be zero.

Question 3

Hint 1: At maximum height, instantaneous velocity is zero, acceleration is not.

Hint 2: What causes a falling object to accelerate on Earth?

Hint 3: Which direction does a falling object accelerate on Earth? The unbalanced force will be in this direction.

Question 4

Hint 1: Work Done = Force × Distance

Hint 2: Power = Energy/Time (In this case the energy is the work done)

Question 5

Hint 1: Moons orbit planets, planets orbit stars, stars form………..

Question 6

Hint 1: As height increases above the Earth's surface, orbital period increases.

Hint 2: Height is above 630 km, so period must be above 97 minutes.

Hint 3: Is 23000 km above or below 36000 km?

Question 7

Hint 1: If the engine is off, there are no forces acting on the probe.

Hint 2: No force is the same as balanced forces.

Question 8

Hint 1: Mass is the amount of matter in an object. It does not change from place to place.

Hint 2: Weight = m×g. if mass, m, is constant and g increases, what has happened to W?

Question 9

Hint 1: a light year is the distance light travels in 1 year

Hint 2: 1 year = 365.25×24×60×60 seconds

Hint 3: The speed of light is 3 x 10⁸ ms^{-1}

Question 10

Hint 1: All spectral ines in an element must be present in the spectrum from the star for the star to contain that element

Question 11

Hint 1: Factual recall: go back to your notes if you can't answer this question.

Question 12

Hint 1: Opposite charges attract, like charges repel

Hint 2: the particle is attracted to Q, it is repelled by R

Hint 3: Particle has opposite charge to Q, same charge as R

Question 13

Hint 1: The thermistor and variable resistor form a potential divider circuit

Hint 2: Supply p.d. is shared according to the proportion of resistance of components

Hint 3: If resistance decreases, p.d. share across that componenet decreases.

Hint 4: p.d. increases across other component (variable resistor in this case)

Hint 5: Transistor switches on.

Question 14

Hint 1: Calculate parallel resistance first

Hint 2: 1/R_{T} = 1/R₁ + 1/R₂

Hint 3: Add series resistance to parallel total

Question 15

Hint 1: P = V²/R

Hint 2: P = 12²/4

Question 16

Hint 1: States of matter in order of coldest to hottest: Solid, liquid, gas

Hint 2: Melting is first change of state

Hint 3: Melting is at first horizontal line

Question 17

Hint 1: Question asks force due to pressure DIFFERENCE

Hint 2: Find force on inside and take away force on outside

Hint 3: P = F/A

Question 18

Hint 1: 1°C is equivalent to 1 Kelvin

Hint 2: Find difference between the two temperatures

Question 19

Hint 1: If volume decreases, pressure must increase

Hint 2: Volume decreases by a factor of 5

Hint 3: Pressure must increase by a factor of 5.

Question 20

Hint 1: Microwaves are shorter than TV waves, so both II and III cannot be correct

Hint 2: REFRACTION occurs when waves pass from one medium to another

Question 21

Hint 1: Gamma has highest frequency and energy of all electromagnetic radiation

Hint 2: X-rays are quite penetrating so have high energy

Question 22

Hint 1: Only A is squared in the equation

Question 23

Hint 1: Be careful with units in this question

Hint 2: How many hours in 30 minutes?

Hint 3: Equivalent dose = Equivalent dose rate × time

Question 24

Hint 1: Half life involves halfing activity

Hint 2: Half the initial activity until you reach 25kBq

Hint 3: Count the number of halves you have done.

Hint 4: Half life = (total time)/(number of half lives)

Question 25

Hint 1: Fission is splitting.

Section 2

Question 1

1a)i)A) Hint 1: For scale diagram, write down your scale

1a)i)A) Hint 2: draw vectors tip to tail

1a)i)A) Hint 3: Measure length of resultant and use your scale

1a)i)A) Hint 4: Draw vectors tip to tail and use Pythagoras' Theorem

1a)i)B) Hint 5: If scale diagram drawn, use protractor to find angle and then bearing

1a)i)B) Hint 6: Use SOH CAH TOA to find the correct angle, then convert to bearing

1a)ii) Hint 7: m = 6.8×10⁴ kg. F_{un} = answer to part (a)(i)(A)

1a)ii) Hint 8: F_{un} = ma

1b) Hint 9: Question mentions fuel decreasing, this means mass decreases

1b) Hint 10: mass and weight are linked by W = mg

1b) Hint 11: P = F/A The Force is W in this case

Question 2

2a)i) Hint 1: Instanteneous speed = (length of card) / (time to pass through gate)

2a)i) Hint 2: Length of card given in question

2a)ii) Hint 3: length of card = 0.045 m, time through gate y = 0.098s

2a)ii) Hint 4: Instanteneous speed = 0.045/0.098

2a)iii) Hint 5: a = ?, u = 0.32ms^{-1}, v = 0.46ms^{-1}, t = 0.56s

2a)iii) Hint 6: a = (v - u)/t

2b) Hint 7: What does area under a v-t graph give?

2b) Hint 8: Area under v-t graph = distance travelled

2b) Hint 9: Area of a triangle = ½ base × height

2c) Hint 10: Trolley decelarates rapidly, then travels in opposite direction, until it comes to rest

2c) Hint 11: The gradient going up and down the hill will be the same.

Question 3

3a) Hint 1: m = 75 kg, v = 8.0 ms^{-1}, E_{k} = ?

3a) Hint 2: E_{k} = ½ mv²

3b)i) Hint 3: Which energy Is gained when raised up away from earth?

3b)i) Hint 4: Apply conservation of energy principles

3b)i) Hint 5: E_{k} = E_{p}

3b)i) Hint 6: E_{p} = mgh

3b)i) Hint 7: g = 9.8 Nkg^{-1}

3b)ii) Hint 8: Where is energy lost to in every situation in National 5 Physics?!

3c)i) Hint 9: cyclist is travelling with constant horizontal speed and constant vertical acceleration

3c)ii) Hint 10: a = 9.8 ms^{-2}, u = 0 ms^{-1}, t = 0.40s

3c)ii) Hint 11: a = (v - u)/t

Question 4

4a)i) Hint 1: 1 AU = 1.5×10^{11} therefore 1.52 AU = 1.52 × 1.5×10^{11}

4a)ii) Hint 2: You need extra information: what is travelling from the Sun to Mars and how fast does this travel?

4a)ii) Hint 3: v = 3.0 x 10^{8} ms^{-1}, d = answer from part (a)(i), t = ?

4a)ii) Hint 4: d = vt

4b)i) Hint 5: You must state the device that converts light to electrical energy

4b)ii) Hint 6: Factual recall: go back to your notes if you can't answer this question.

Question 5

Hint 1: OEQ - Consider, are astronauts weightless? Do they float? What is the ISS doing to stay in orbit?

Question 6

6a) Hint 1: The circuit is a potential divider

6a) Hint 2: V_{s} = 4V, R_{1} = 2.0Ω, R_{2} = 18Ω

6a) Hint 3: V₂ = (R₂/(R₁+R₂))×V_{s}

6b)i) Hint 4: Are LEDs high or low current devices?

6b)i) Hint 5: What happens to current in a circuit when you increase resistance?

6b)ii) Hint 6: V_{s} = 3.4V, I = 25mA = 0.025A, V_{led} = 1.6V, R = ?

6b)ii) Hint 7: To find R, you will need information about the resistor. Current is given in the question.

6b)ii) Hint 8: The pd across resistor = V_{s} - V_{led}

6b)ii) Hint 9: Now use V = IR to find resistance

6c) Hint 10: Q = ?, t = 6 hours, I = 0.135A

6c) Hint 11: t should be in seconds

6c) Hint 12: There are 60 × 60 seconds in an hour

6c) Hint 13: Q = It

6c) Hint 14: Q = It = 0.135 × 6 × 60 × 60

Question 7

Hint 1: What happens to a wire if current passes through it?

Hint 2: What happens to gas in a sealed container if the temperature increases?

Question 8

8a)i) Hint 1: E_{h} = 21 600J, m = 0.50kg, ΔT = 24 - 16

8a)i) Hint 2: E_{h} = mcΔT

8a)ii) Hint 3: Calculation assumes all heat energy goes into the water. Does it?

8a)ii) Hint 4: Where does the energy go?

8b) Hint 5: I = 4.0A, V = 12V, E = 21 600J, t =?

8b) Hint 6: Can you think of an equation that links t to any of the information given?

8b) Hint 7: P = E/t

8b) Hint 8: To find P we need to use I and V (P = IV)

8c) Hint 9: Vapourisation is changing state from liquid to gas

8c) Hint 10: Temperature stays the same for state change, so is not required in calculations

8c) Hint 11: The equation including l is E = ml and in order to calculate l we would need m and E - what do these letters mean?

Question 9

9a)i) Hint 1: All data means you must use all 8 numbers in the question

9a)i) Hint 2: p/T should be constant

9a)i) Hint 3: Calculate p/T for each set of data

9a)ii) Hint 4: The kinetic model describes gas as small particles moving around.

9a)ii) Hint 5: If temperature increases, what happens to the kinetic energy of particles?

9a)ii) Hint 6: The increase in temperature causes an increase in kinetic energy. How will this affect how often particles hit the walls?

9a)ii) Hint 7: The increase in temperature causes an increase in kinetic energy. How will this affect how much Force particles hit the wall with?

9a)iii) Hint 8: Your answer from part (a)(i) might help

9a)iii) Hint 9: For every 20K temperature drop, there is between 6 and 9 kPa pressure drop

9b) Hint 10: What can be changed to ensure all of the gas in the flask is being heated?

9b) Hint 11: Is the gas in the small tube being heated? How could you reduce the impact of this on the experiment?

Question 10

10a) Hint 1: t = 2.1 × 10^{-8}s, d = ?

10a) Hint 2: The equation linking t and d is d = vt

10a) Hint 3: Do you know the speed of microwaves?

10a) Hint 4: Microwaves travel at the speed of light (it is on the data sheet on page 2 of the exam)

10a) Hint 5: d = vt = 3×10^{8} × 2.1×10 ^{-8}. Be careful when entering this in your calculator.

10b)i) Hint 6: Longitudinal refers to the direction of energy tranfer and vibration of the medium

10b)ii) Hint 7: count the number of waves in the picture (more lines together is the start and end of a wave)

10b)ii) Hint 8: wavelength = (total length)/(number of waves)

10b)ii) Hint 9: wavelength = 0.272/4

10b)iii) Hint 10: We are taking about sound waves, so be careful with speed

10b)iii) Hint 11: λ = answer from part (b)(ii), v = 340 ms^{-1}, f = ?

10b)iii) Hint 12: v = fλ

10b)iii) Hint 13: 340 = f × 0.068

Question 11

11a)) Hint 1: Factual recall: can you remember the list of IR detectors?

11a)) Hint 2: The one you pick must be suitable for use with a windscreen

11b)) Hint 3: What is the definition of frequency?

11b)) Hint 4: Frequency = (number of waves)/(vibrations per second)

11b)) Hint 5: At 70% light received, number of raindrops is in the medium zone (from graph)

11b)) Hint 6: N = 54 (per minute)

11b)) Hint 7: f = 54/60

11c)i)A) Hint 8: A normal is a line at right angles to the surface at the point the light enters/exits

11c)i)B) Hint 9: the angle of incidence is the angle between the ray and the normal heading toward the surface boundary

11c)i)B) Hint 10: angle of refraction is the angle between the ray and the normal heading away the surface boundary

11c)ii) Hint 11: Light is refracting away from normal in glass

11c)ii) Hint 12: therefore wavelength must be greater in water.

11c)ii) Hint 13: frequency is constant, therefore wavelength is greater in water.

11c)ii) Hint 14: Light must be speeding up in water

Question 12

12a)) Hint 1: There are 3 types of radiation: one is comprised of 2 neutrons and 2 protons, one is a fast moving electron and one is high frequency electromagnetic radiation.

12b)) Hint 2: What happens to the activity of a radioactive source over time?

12b)) Hint 3: Approximately how many half lives have occurred?

12b)) Hint 4: Appoximately how many of the radioactive nuclei have decayed?

12b)) Hint 5: What effect will a reduction in tritium nuclei have on the ability of the coating to emit visible light?

12c)i) Hint 6: D = 0.40mGy = 0.0004Gy, m = 85 kg, E = ?

12c)i) Hint 7: D = E/m

12c)i) Hint 8: 0.0004 = E/85

12c)ii) Hint 9: D = 0.0004Gy, H = ? Is there any other information that we can get fom the question?

12c)ii) Hint 10: The source is emitting Beta radiation

12c)ii) Hint 11: All radiation has an associated weighting factor: they are on page 2 of the exam paper.

12c)ii) Hint 12: W_{r} = 1

12c)ii) Hint 13: H = D×W_{r}

Question 13

13a)i) Hint 1: Background radiation is always present.

13a)i) Hint 2: If you are trying to measure the radiation from a particular source, what do we need to do with the background radiation count?

13a)ii) Hint 3: Factual recall: can you remember the list of background sources?

13b)i) Hint 4: Think what makes a good graph.

13b)i) Hint 5: Axis labels with units

13b)i) Hint 6: Consistent scales

13b)i) Hint 7: Accurately plotted data

13b)i) Hint 8: Dependent variable on vertical axis (corrected count rate) and Independent variable on horizontal axis (time).

13b)ii) Hint 9: You are trying to find the time it takes for the source activity to half.

13b)ii) Hint 10: Pick an activity value that is easy to half, say 600, note the corresponding time.

13b)ii) Hint 11: Half the activity, find corresponding time

13b)ii) Hint 12: Half life is the difference between these times.

13c)i) Hint 13: How far can alpha particles travel in air?

13c)i) Hint 14: Will alpha radiation reach the detector as currently setup?

13c)i) Hint 15: What needs to change to allow alpha particles to reach the detector?

13c)ii) Hint 16: A = 520Bq, t = 15s, N = ?

13c)ii) Hint 17: A = N/t

13c)ii) Hint 18: 520 = N/15

Did this hint help?