Waves in Air, Fluids & Solids (AQA GCSE Physics: Combined Science)

Figure 3 shows a transverse wave.

Figure 3

Which of the arrows shown in Figure 3 correspond to the waves:

Amplitude ____________

Wavelength ____________

Some students plan to investigate the properties of water waves.

Figure 4 shows the apparatus that they decide to use.

Figure 4

Describe a method that they could use to measure the speed, frequency and wavelength of the waves.

The ripple tank produces waves with a time period of 24 milliseconds.

Calculate the frequency of the waves.

Give your unit

Give your answer to 3 significant figures.

Two girls stand some distance away from a wall and clap two wooden blocks together. The sound from the blocks reflects from the wall, producing an echo.

They then continue to clap the blocks together, timing each clap so it is in time with each echo.

This is shown in Figure 5 below:

Figure 5

Describe how they can use the above method to determine the speed of sound, stating clearly what measurements they must take.

The girls estimate the speed of sound to be 340 m / s.

The sounds they produce have an average frequency of 1020 Hz.

Calculate the wavelength of the sound waves.

P-waves travel with an average speed of about 7000 m/s.

Some P-waves are produced by a minor earthquake and detected a short while later by a seismometer 3000 km away.

Calculate how long it will take the P-waves to reach the seismometer.

On a beach popular with surfers, one is watching a buoy move up and down with the waves, in Figure 1. 

Figure 1

She decides to plot a graph of how the height of the buoy varies with time - this is Figure 2.

Figure 2

Using a stopwatch, she measures the time from the buoy at its highest point to the peak of the 7th and smallest wave.

This takes 24.5 s.

Calculate the frequency of the waves.

Give your answer to 2 significant figures.

The surfer knows the distance to the buoy from the shore. 

Describe a method by which the surfer could determine the speed of the waves accurately.

The surfer determines that the wave speed is a value between 3.5 m/s and 4.5 m/s.

Calculate the possible range of wavelengths of the waves.

Give your answers to 2 significant figures.

Suggest why the surfer could only give a range of values for wave speed.

Students in a classroom are trying to calculate the speed of different waves along a string. The equipment provided is shown in Figure 1.

Figure 1

Describe an experiment, using the equipment in Figure 1, that would allow the students to determine the wave speed of different waves along the string.

The students double the frequency each time they perform the experiment and sketch the waves they observe. These sketches are shown in Figure 2.

Figure 2

One of the student makes the conclusion:

"The frequency is doubling so the speed must also be increasing".

Explain why this statement is incorrect and describe how the speed varies.

The students finish early and start a second experiment to study the effect of varying tension force in the string. 

They add mass to the end of the string and vary the frequency until they produce the following wave on the string:

Figure 3

They then add more mass and change the frequency until the pattern from Figure 3 appears again.

They then determine the tension and wave speed at each wave speed.

State the dependent and independent variables in their experiment. 

Name the variable the students must control in this second experiment.