Vibrations and Waves

 

 

1.      Mass on a spring

A mass hanging from a spring will oscillate with a period we’ll call T.  We want to know if T depends on the value of the mass m, and if so, we want to know as much as we can about that dependence.  The period is the time for one complete cycle (bottom to top and back to bottom again, for instance).  It is most effective to measure T by timing 10 (or 20) oscillations and dividing by 10 (or 20).  Use the spring and masses you are provided to determine

 

(a)    does the period depend on the amplitude of the oscillations?

 

(b)    How does the period depend on the mass m?  Be as quantitative here as you can be.  Plotting a graph (I have some graph paper) is a useful approach.

 

2.      Pendulum

This experiment is similar to the spring experiment in nature…you are to find out what factors determine the period of a pendulum.  I will give you string, washers to serve as the weight at the bottom of the string, and timers and rulers.  And you are to design and execute whatever experiments you choose to determine the factors upon which the period depends, and to explore the nature of that dependence. 

 

3.      Now that you know all about springs and pendulums, see if you can answer these questions: 

(a)    If I hang a mass m = 2 kg from a spring, it has a period of 2 seconds.  If I hang a mass of 8 kg from the same spring, what will its period be?

(b)    If I double the length of a pendulum, what happens to its period?

 

4.      Slinky waves

Use the slinky to investigate the properties of waves.  You should do the following, and describe your observations below:

(a)     generate both longitudinal and transverse waves.

(b)    Show how the wavelength changes when you change the frequency

(c)     Determine how to increase the speed of waves on the slinky

(d)    Generate standing waves:  see if you can form standing waves with zero, one and then with two nodes (excluding the ends).  Sketch them below.

 

 

 

 

 

 

 

 

 

5.      If water waves have a wavelength of 0.2 meters, and it is observed that a leaf on the surface bobs up and down every 0.3 seconds as the wave goes by, what is the speed of the waves?

 

 

 

 

6.      If I hear the thunder 5 seconds after seeing the lightning flash, how far away is the lightning?