Name: _______________________________________________

CS P1 F Waves

Date:

Time: 28 minutes

Total marks available: 28

Total marks achieved: ______

Questions Q1.

There is a piece of music called "The Flight of the Bumble Bee." This takes 4 minutes to play. During this time, a bee flies 1608 m.

Calculate the average speed of the bee.

(3)

speed ........................................................... m/s

Q2.

A wave has a frequency of 15 Hz. Its wavelength is 125 m.

Calculate the speed of the wave.

State the unit.

(3)

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Q3.

The electromagnetic spectrum is continuous. Different regions of the spectrum have different properties. An electromagnetic wave has a frequency of 7 × 109 Hz. The speed of the wave is 3 × 108 m/s. Calculate the wavelength of the wave.

(3)

wavelength = .....................m

Q4.

Light and sound waves are produced at the same time by an explosion on Earth.

(i) The sound of the explosion is heard 1920 metres away 6.0 seconds after the explosion has happened.

Calculate the speed of sound in air. (2)

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(ii) A scientist is standing a long way from the explosion.

Explain why he hears the explosion a few seconds after he sees it. (2)

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Q5.

The diagram shows a transverse wave.

(i) Use words from the box to label the distances X and Y.

(2)

(ii) Q is a particle in the wave.

Which of these shows the way in which particle Q moves?

Put a cross ( ) in the box next to your answer. (1)

Q6.

(i) The diagram represents a wave.

State the amplitude and wavelength of the wave.

(2)

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(ii) 20 waves are sent out in 4 seconds.

Complete the sentence by putting a cross ( ) in the box next to your answer.

The frequency of the wave is

(1)

A 0.2 Hz

B 5 Hz

C 20 Hz

D 80 Hz

Q7.

A man throws a stone into a pond.

On the other side of the pond, the water becomes very shallow.

In the shallow water, the wave is slower but the frequency does not change.

State what happens to the wavelength when a wave reaches the shallow water.

(1)

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(Total for question = 1 mark)

Q8.

A man throws a stone into a pond.

The stone makes waves that spread out in circles.

Figure 4 shows some of the waves.

Figure 4

(i) Which of the following changes is correct as the waves spread out?

(1)

A the amplitude is higher

B the frequency is higher

C the wavefront is longer

D the period is longer

(ii) The stone hits the water 4.0 m from the bank.

The wave speed is 0.70 m/s. Calculate the time for the wave to reach the bank.

(2)

time = ........................................................... s

(iii) The wavelength of the waves is the distance between one wavefront and the next.

Use the diagram to find the wavelength of the waves. (1)

wavelength = ........................................................... m

(iv) There is a cork which bobs up and down in the water as the wave goes past.

Explain how this shows that the wave is transverse. (2)

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(Total for question = 6 marks)

Q9.

Figure 2 shows a water wave.

Figure 2

(i) What is the amplitude of this wave?

(1)

A 2.8 cm

B 5.6 cm

C 7.5 cm

D 15 cm

(ii) What is the wavelength of this wave?

(1)

A 2.8 cm

B 7.5 cm

C 15 cm

D 30 cm

(Total for question = 2 marks)

Examiner's Report Q1. In this 'cultural' question, a change of unit was required to finish with the unit given. The most common erroneous response involved just the numbers as stated i.e. 4 minutes.

Results Plus: Examiner Comments Many candidates built the change into their substitution. This scored all three marks.

Results Plus: Examiner Comments This scored 2 marks, as it missed the change of unit.

Results Plus: Examiner Comments Some candidates found it hard work gaining the one mark for change of unit.

Q2.

All except the weakest candidates scored 2 marks. A common incorrect answer was 8.33 (because of 125 ÷ 15).

The unit mark was awarded much less frequently, 'Hz' or 'V' were popular errors, 'mps' was also

a common incorrect response.

Results Plus: Examiner Comments This is an example of a typical 2-mark response. Clearly the candidate thinks that the 'V' in the formula represents voltage.

Results Plus: Examiner Comments This response gained 2 marks – 1 mark for the correct substitution and 1 mark for the correct unit for speed.

Q3.

Almost 60% of candidates scored at least one mark for this item with almost 30% scoring all three marks. It was pleasing to note that many candidates are now writing the equation, transforming it and then making the substitution. However, having transformed the equation

correctly, putting the smaller number on top seems to present a problem for some candidates. A number of candidates appeared either not to have a calculator or not to be familiar with how to use it for standard form.

An example of one of the 3 mark responses:

Results Plus: Examiner Comments Although not all the working is included, there is sufficient for the examiner to award 2 marks if the answer had been incorrect.

Results Plus: Examiner Tip Triangles are a good way to help to remember some equations BUT, the examiner will not award any marks for them.

A typical 2 mark response:

Results Plus: Examiner Comments This response shows good evidence of the candidate's method of working. This allows the examiner to award 2 marks as unfortunately, the candidate has made a power of ten error when converting the speed from standard form.

Results Plus: Examiner Tip Candidates should always show their working. If they get the answer correct with no working, then they will get full marks but if their answer is wrong with no working, they

will get zero.

Q4.

(i)

Distance and time are given in order to calculate speed. The equation should be found on the formulae page, values substituted and then a calculator used to find the answer if candidates find division difficult.

Results Plus: Examiner Comments No marks were awarded for this response. The candidate has wrongly remembered the triangle. Although knowing equations is useful, candidates should know that they are at the front of the paper and can be looked up.

Results Plus: Examiner Tip Use the formulae sheet at the front of the paper.

Results Plus: Examiner Comments 1 mark is awarded as the substitution is correct but the answer was not given correctly.

Calculators should be made available to candidates.

Results Plus: Examiner Tip Bring your calculator to the examination.

Results Plus: Examiner Comments This is an excellent example of how the calculation should be carried out. 2 marks were awarded.

Results Plus: Examiner Tip Always include your working.

(ii)

About half of candidates appreciated that the explosion was seen before it was heard because light travels faster than sound. However, some candidates did not appreciate that light travelled at a particular speed and took a finite time to reach the scientist and concentrated on trying to explain why sound travelled slowly with no reference to the light.

Results Plus: Examiner Comments 1 mark was awarded. The candidate has the idea of a difference in speed between light and sound but gets it the wrong way around.

Results Plus: Examiner Comments The question tells the candidates that the sound takes longer to travel to the scientist than the light. The point is 'Why is this so?' The answer must have some reference to speed.

Results Plus: Examiner Tip Make sure you do not just repeat the question in another way.

Results Plus: Examiner Comments This is a concise correct answer. 2 marks were awarded.

Q5.

(i)

Nearly all candidates managed to correctly label at least one of the two. Wavelength was the most popular correct answer although sometimes this was incorrectly labelled frequency.

Q6.

(i)

Most candidates knew what is meant by amplitude of a wave and, compared with previous series, there were far fewer candidates who confused amplitude with peakto- peak value.

Many candidates also knew how to find the wavelength of a wave and so answered this part of the question correctly.

Q7. No Examiner's Report available for this question Q8. No Examiner's Report available for this question Q9. No Examiner's Report available for this question

Mark Scheme Q1.

Q2.

Answer Acceptable

answers Mark

Substitution into correct equation(1) v = 15 × 125 Evaluation (1) 1875 Unit (1) m/s

Power of 10 error max 1 mark for numerical answer 2 marks for correct numerical answer even with no working shown ms-1not mps 1.875 km/s or 6750 km/h gain 3 marks If numerical answer incorrect, accept any correctly-written unit of speed: eg km/s or km/hr or miles per

(3)

hour / mph

Q3.

Answer Acceptable

answers Mark

transposition λ = v/f (1) substitution λ = 3 × 108/7 ×109 (1) evaluation 0.043 (m) (1) Ignore any unit given by candidate

Subst. and transform. either order 1 mark only can be scored for correct substitution after incorrect transposition. 3 × 108/7 ×109 gains 2 marks Accept any number of sig.figs. that rounds to 0.04 0.04 , 0.0428 (m) (1) Give full marks for correct answer with no working. 0.04 × any other power of 10 = 2 marks (3)

Q4.

Answer Acceptable

answers Mark

(i) Substitution v = 1920/6.0 (1) Evaluation (1) 320 (m/s)

300 (m/s) give full marks for correct answer, no working (2) Power of 10 error max. 1 mark.

(2)

(ii) Suggestions including the following:

recognition of any difference in speed / velocity (1)

correct difference in speed (1)

e.g. sound travels faster / quicker than light (1) c>v / v<c / c>320 (m/s) Light travels (much) faster (2) RA Ignore 'sound takes longer' or other references to time.

(2)

Q5.

Q6.

Answer Acceptable

answers Mark

(i) 5 (cm) (1) 8 (cm) (1)

+5 -5 0.08 m 80 mm

(2)

(ii) B (1)

Q7.

Q8.

Q9.