Fun With Springs

1.0 Purpose: - to investigate pulses in springs

2.0 Background: - Demo,

• Incident Pulse
• Transmitted Pulse
• Reflected Pulse
• Positive Pulse,
• Negative Pulse,
• Speed of a Wave
• Fixed and Free end
• Connecting springs
• ( Phase - optional)

3.0 Design: - Students design a series of informal experiments (activities) to answer the following questions.

4.0 Materials: - Slinky Spring, Long Spring, String, Stop Watch,

5.0 Questions: -

5.1 Investigate the speed of a wave (pulse) in a spring

Q1 Is the speed affected by amplitude, if so how?

Q2 Is the speed affected by tension, if so how?

Q3 Which spring is "faster" than the other. (remember to consider control variables)

5.2 Investigating Reflection

Q4 How does a pulse reflect from a free end vs. a fixed end? (orientation, delay, phase)

5.3 Investigating Transmission - Attach springs together and send a pulse from slow to fast and from fast to slow. Observe

Q5 What does Partial Reflection mean.

Q6 Complete the following table. (+ means positive pulse orientation, - would mean negative pulse orientation)

Medium Change	Incident Pulse Orientation	Reflected Pulse Orientation (+ or -)	Transmitted Pulse Orientation (+ or -)	Relative Wavelength of Transmitted Pulse (longer or shorter than incident wavelength)
Fast to Slow	+
Slow to Fast	+

5.4 Interference of Waves (pulses) - Have two students hold each end of a spring. Each student send a positive pulse down the spring and observe what happens when they meet. Try again with two negative pulses and with one positive and one negative pulse. Try to make the amplitudes the same.

Q7 What resultant occurs when waves meet?