20.3.5 Observe and explain Observe the series of sketches at the right. The pulses travel at speed v along the string of length L. Based on your analysis and using these two quantities, decide the time interval T (called the period for the first vibration) between upward pulls of the hand so that each upward pull sup-b. ports or enhances the pulse that has just returned to and reflected from your hand after one trip down the string and back. The frequency of these upward pulls c is.fi-|/т,. The vibration that is produced is called the fundamental or first harmonic standing wave vibration, and its frequency is labeled a. d. e. h. k. 20.3.6 Observe and explain Observe the series of sketches at the right. The puises travel at speed v along the string of length L. Note that as the hand is initiating an upward pulse, as in part a, an earlier pulse has reflected fro the right and is starting its return to the hand. Based on your analysis and the quantities and L, decide the time interval T2 between upward pulls of the hand so that each upward puli supports or enhances this second vibra tion. The frequency of this vibration is/T2. This is called the second harmonic standing wave vibra- tion, and its frequency is labeled . Note: N desig- nates a node (a point at which the string does not vibrate); A designates an antinode (a point at which the string has its maximum amplitude vibration). b. C. d. e. 20.3.5 Observe and explain Observe the series of sketches at the right. The pulses travel at speed v along the string of length L. Based on your analysis and using these two quantities, decide the time interval T (called the period for the first vibration) between upward pulls of the hand so that each upward pull sup-b. ports or enhances the pulse that has just returned to and reflected from your hand after one trip down the string and back. The frequency of these upward pulls c is.fi-|/т,. The vibration that is produced is called the fundamental or first harmonic standing wave vibration, and its frequency is labeled a. d. e. h. k. 20.3.6 Observe and explain Observe the series of sketches at the right. The puises travel at speed v along the string of length L. Note that as the hand is initiating an upward pulse, as in part a, an earlier pulse has reflected fro the right and is starting its return to the hand. Based on your analysis and the quantities and L, decide the time interval T2 between upward pulls of the hand so that each upward puli supports or enhances this second vibra tion. The frequency of this vibration is/T2. This is called the second harmonic standing wave vibra- tion, and its frequency is labeled . Note: N desig- nates a node (a point at which the string does not vibrate); A designates an antinode (a point at which the string has its maximum amplitude vibration). b. C. d. e.