# Assignment_ Waves on a String

Open the simulation, Set to “Pulse”; “Fixed End”; Damping = None; Tension = Low. Turn the Ruler and Timer ON. The simulation speed should be Normal (you can change to slow motion if you prefer). The amplitude is set to 0.75 cm and pulse width to 0.50s by default

Question 1:

Report your measurement of length of the beaded string from the pulse generator the clamp, L, with its uncertainty in the proper format of with the same number of decimal places and units of meters.

 L (with uncertainty in m) =

Click the button on the pulse generator to send a pulse through the string. Use the timer to measure how long it takes for the pulse to make 5 round trips (travel back and forth 5 times) on the string. While you could time the pulse for a single pass on the string, it will be much more accurate to allow the pulse to travel multiple trips and calculate an average value. Record the time below in seconds with the uncertainty in the digital timer. Then divide by 5 to find the time for the pulse to make one round trip.

 Δt5 round trips (with uncertainty in s) = Δt1 round trip (no uncertainty, s) =

Repeat the time measurements with Tension set to Medium and then High. Perform all necessary calculations to find the speed of the wave for one round trip on the string. Fill in the table below (you do not need to include uncertainties in the table). Make sure that you multiply the length of the string by 2 for the total round trip distance.

 Tension Time for pulse to travel 5 round trips [s] Time for pulse to travel one round trip [s] Length of one round trip [m] Speed of wave () [m/s] Low Medium High

Question 2:

In the simulation, set to “Oscillate”; “No End”; Damping = None; Amplitude = 0.75 cm. Keep the Ruler and Timer ON. Set the simulator speed to slow motion.

Set the Frequency to 1.00 Hz and the Tension to LOW. Similar to the last example we are going to calculate the speed of the wave by measuring the distance and time of travel. Since there is no reflection point for the wave, we cannot use round trips, so consider that when establishing your measurement uncertainty. Measure the distance and time it takes for a wave to travel the length of the string. Record both below with uncertainty.

 L (with uncertainty in m) = Time for wave to travel the length of string (with uncertainty in s) =

Calculate the speed of the wave on this string using distance and time,

 v (in m/s) =

You can also measure the speed of a wave using wavelength and frequency,. For the set frequency, use the ruler to measure the length of a single wavelength with uncertainty in meters. Recall that the wavelength is the distance that the wave repeats itself. (Hint:  Let the wave oscillate, and then pause the motion.)

 λ (with uncertainty in m) =

Calculate the speed of the wave using wavelength and frequency, (Hz=1/s)

 v (in m/s) =

Calculate the % difference () in these two values of speed of the wave. If you have more than 15% difference, then go back and look at your measurements and calculations, or contact your lab instructor for help.

 % difference (in %) =

Repeat the measurements with the frequency set to 2.0 Hz and 3.0 Hz. Then change the Tension to Medium and then High and repeat for those tension settings. Perform all necessary measurements and calculations to fill in the table below (you do not need to include uncertainties in the table but do use sig figs and units).

 Tension Frequency Wavelength Speed using Distance travelled Time travelled Speed using Low 1.00 Hz Low 2.00 Hz Low 3.00 Hz Medium 1.00 Hz Medium 2.00 Hz Medium 3.00 Hz High 1.00 Hz High 2.00 Hz High 3.00 Hz