Monday 26 April:

L#74: 1- 2, 9, 10, 15, 16, 20

(due Monday 26th) (2nd law of Thermodynamics)

L#78: 1- 2, 8, 11, 12, 14, 15 -19

(due Wed (28th) (Standing Waves)

Lab: Tues 27th   (Get the cold out)

Test 69,70,71,74,78 

Friday 30 Apr or Mon 3 May      (:>

Transverse Wave:        Particles vibrate in a direction perpendicular to the wave direction & velocity.

Longitudinal Wave:     (also Compression, or Shock ) Particles vibrate in a direction parallel to wave direction & velocity.

Two formulas:

V = f  l

V = √(T/M_L)

Ex: a. If the tension is 100N and the M_L is 9-kg/m, What is the speed on the string?

a. V = √(T/M_L) = √(100/9) = 10/3 or 3.33...

b. If the M_L becomes 36-kg/m (four times the M_L, what is the velocity now compared to case a.?

b. V = √(T/M_L) = √(100/36) = 10/6 or 1.66...

Beat Frequency:

The number of beats is the difference in the frequencies

Continuous Wave:       A series of equal pulses equally spaced moving together.

Standing wave:           When a continuous wave strikes a barrier and reflects back on itself it will create an interference pattern (see interference below).  If the phase (see phase below) of the reflected wave is exactly opposite to the incoming wave they will superimpose creating a standing wave.

Node:      A point on a standing wave that does not move at all.

Speed depends on the mediums elasticity.  When a wave travels from one medium to a different medium the speed & wavelength change.  However the frequency remains the same.

Strings:      Only multiples of ½ wavelengths can fit on a vibrating string that is held fixed at each end. Nodes on each end always

 Fundamental Frequency

1st Harmonic     2nd Harmonic                  3rd Harmonic


 

Open Tubes:    Same as strings, multiples of ½ waves.  But the waves look a little different, since the ends aren’t fixed. Anti-nodes at the ends

Closed end (One-end) Tubes:  Closed tubes hold multiples of ¼ waves. Nodes at closed end and anti-node at open end