PIRA Code(s): 3A10.20
Set up time:1 minute
Operation: Move the weight along the hacksaw blade. Pull back on the blade and release. When the weight is at the top of the blade the frequency is smaller compared to when the weight is at the bottom.
Physics and Science Concepts: Oscillations
Safety: Edge of blade may be sharp.

PIRA Code(s): 3A10.40
Set up time:none
Operation: Push the pendulum so that it swings back and forth at an angle of about 0 º. Then, slowly increase the angle, and watch the frequency decrease. For a more effective demonstration, start the pendulum at a relatively high angle, and then decrease the angle of the plane of oscillation so that the frequency of the pendulum will increase over time.
Physics and Science Concepts: Oscillations
Safety: None

PIRA Code(s): 3B30.30
Set up time:10 minutes (5 minutes to pump the bell jar)
Operation: Plug in the pump and attach the clear tube of the pump to the valve. Turn the switch on the power supply to ascertain that the alarm is working properly. Then, pump out the air inside the bell jar. It will take about 5 minutes to obtain a low enough air pressure so that the alarm will not sound. Turn the alarm on and slowly open the valve, allowing the air pressure in the bell jar to increase. The sound of the alarm will also gradually increase.
Physics and Science Concepts: Sound waves
Safety: A glass jar containing a vacuum can be extremely hazardous if broken.

PIRA Code(s): 3D46.16
Set up time:no setup required
Operation: Place the boxes with open cavities facing, one box length apart. Strike the first tuning fork with the striker. Stop the vibrations with your hand. Listen closely for the sound coming from the second fork.
Physics and Science Concepts: Waves and Oscillations
Safety: None