PASCO WA-9857 - Manual

Model No. WA-9857 Equipment Setup 5 ® Rod Clamp The case of the String Vibrator has a built-in rod clamp for mounting it either horizontally or vertically on a rod with a diameter up to 12.7 mm (1/2 inch). Slide the rod through the case in the preferred orientation and tighten the thumb screw. The U...

String Vibrator Equipment Setup 6 ® Vertical String The vertical arrangement with the elastic cord makes a good classroom or lecture demonstration. It requires a vertical rod and a horizontal component at the top of the rod, such as a Pendulum Clamp (SE-9443), to attach the elastic cord. To adjust t...

Model No. WA-9857 Equipment Setup 7 ® Good Nodes Versus Bad Nodes Most demonstrations and experiments involve adjusting the length, tension or frequency to produce a standing wave pattern. It is tempting to look only at the amplitude of the wave and concentrate on making it as large as possible; but...

String Vibrator Introductory Activity 8 ® I n t r o d u c t o r y A c t i v it y This activity works best with two or more people. 1. Attach the String Vibrator to the table. You’ll be stretching the cord to about 2 m, so leave enough space. 2. Cut 1 m of elastic cord and attach one end to the vibra...

Model No. WA-9857 Demonstration 1: String Density and Wavelength 9 ® De m o n s t r a t i o n 1 : St r i n g D e n s i t y a n d Wa v e l e n g t h *The recommended inelastic cord (PASCO part ME-9876) has a linear density of 1.5 g/m. **This demonstration is easier to set up with a Sine Wave Generato...

String Vibrator String Density and Wavelength 10 ® 4. Loosen the clamp on the String Vibrator and slide it along the table to adjust the length of the vibrating part of the inelastic cord. Adjust it so that knot connecting the elastic and inelastic cords is at a node. (The amplitude may be low, but ...

Model No. WA-9857 Demonstration 2: Closed Tube Analogy 11 ® De m o n s t r a t i o n 2 : C l o s e d Tu b e A n a l o g y *With a Sine Wave Generator (ME-9867), or another a ±10 V, 1 A function generator in place of the fixed-frequency power supply, this demonstration is easier to set up, and requir...

Model No. WA-9857 String Vibrator 13 ® E x p e r i me n t 1 : Wa v e Sp e e d Introduction In this experiment you will determine the wave speed in a stretched string using three methods. First, you will calculate the speed based on the wavelength and frequency of a standing wave in the string. Next,...

String Vibrator Wave Speed 14 ® 2. Cut about 1 m of elastic cord. Measure its exact unstretched length. Measure the mass using a balance. Calculate the Unstretched Linear Density (mass/length). (If your balance is not precise enough to measure 1 meter of cord, measure the mass and length of a much l...

Model No. WA-9857 Experiment 1: Wave Speed 15 ® Wave Speed Calculated from Tension and String Density You can also calculate the wave speed from the tension (F ) and the linear density ( µ ) of the cord with: (eq. 2) The linear density is the mass per unit length of the cord when it is stretched. Th...

String Vibrator Wave Speed 16 ® 4. Start recording data just before you pluck the string, then immediately stop recording. 5. View the force and voltage data on a graph, and find the elapsed time, ∆ t, between the sudden decrease in tension and the change in voltage. 6. Calculate the pulse speed: (e...

Model No. WA-9857 String Vibrator 17 ® L = L = l l 3 2 L = l 1 2 E x p e r i me n t 2 : Sta n d in g Wa v e s I n Str i n g s Purpose The general appearance of waves can be shown by means of standing waves in a string. This type of wave is very important because most of the vibrations of extended bo...

String Vibrator Standing Waves In Strings 18 ® adjusted to the frequency of the driving vibrator, one vibrational mode will occur at a much greater amplitude than the other modes. For any wave with wavelength λ and frequency f, the speed, v, is (eq. 1) v = λ f The speed of a wave on a string is also...

Model No. WA-9857 Experiment 2: Standing Waves In Strings 19 ® Procedure 1. Adjust the tension by adding to or subtracting from the hanging mass so that the string vibrates in 2 segments. Adjust the tension further to achieve a “clean” node at the center. Also check the end of the vibrating blade; t...

String Vibrator Standing Waves In Strings 20 ® 2. For every value of mass, calculate the tension (including uncertainty) in the string. Tension = F = m g 3. Make a graph of F versus n . Describe in words the shape of the graph. 4. For every value of n , calculate 1/n 2 . Make a graph of F versus 1/n...

Model No. WA-9857 String Vibrator 21 ® E x p e r i me n t 1 : Te a c h e r s ’ N o t e s – Wa v e Sp e e d Equipment Notes Clamps Instead of table clamps and rods, you can use two C-clamps to fasten the String Vibrator and force sensor to the table. Use a block or book to elevate the force sensor a ...

Model No. WA-9857 Experiment 2: Teachers’ Notes–Standing Waves In Strings 23 ® Be sure to measure from the sudden force change, not the relatively slow variation that may occur before the actual pluck. It may be helpful to repeat the measurement a few times and take the average value. ∆ t = 3.4 × 10...

String Vibrator Teachers’ Notes–Standing Waves In Strings 24 ® Analysis Method 2 f = (60.0 ± 0.1) HzL = (0.987 ± 0.001 m) This result differs from the direct measurement of linear density by 0.01 × 10 -4 kg/m. It is within the estimated uncertainty. F vs. n F vs. 1/ n 2 Slope = 3.74 ± 0.01 N 4 µ f 2...

Model No. WA-9857 String Vibrator S a fe ty Read the instructions before using this product. Students should be supervised by their instructors. When using this product, follow the instructions in this manual and all local safety guidelines that apply to you. Te c h n i c a l S u p p o r t For assis...