High speed and high resolution. Breakthrough ADC technology switches from 8 to 16 bits in the same oscilloscope.
This activity is in the A2 unit Build or Bust? and links together the work on earthquake waves, simple harmonic motion and properties of materials. It is immediately preceded by an activity in which a pulse is sent down a row of trolleys, modelling on a large scale, what is happening within the metal bar.
Speed of wave by experiment = 2 x 0.700 m/401 µs = 3490 m·s -1.
Speed of wave by formula = 5090 ms -1.
The differences in values obtained reflect the anisotropy of the rods used, the degree of cold working they underwent in manufacture, variations in E and with temperature, the extent to which shear forces come into play and so present a need to take the Bulk Modulus into account, as well as the uncertainty in the experimental results.
Students may note, especially with ADC-40/42, that the fall in voltage after contact is lost looks somewhat exponential. This is likely to reflect an RC component in the interface and might provide a timely reminder of this type of decay.
*For steel and aluminium you may be able to utilize retort stand rods.
Attach a 0.7 m length of red connecting wire to the hammer neck via a hose clip and terminate the other end with a red 4 mm plug.
Attach a 0.7 m length of red connecting wire to the metal rod via a hose clip and terminate the other end with a red 4 mm plug. Ensure that the areas of contact are cleaned with emery cloth first.
If a DrDAQ is being used attach a 0.7 m length of red connecting wire to its V terminal and terminate with a red 4 mm plug. Similarly attach a 0.7 m length of black connecting wire to its GND terminal and terminate with a black 4 mm plug.