ACTIVITY 1: LET’S MAKE WAVESBoard work: Draw three sketchesof the rope showing the motionof the pulse at three subsequentinstances (snapshots at threedifferent times).Draw an arrow to represent thedirection of the pulse’s motion.
BASED ON THE ILLUSTRATION SHOWNON THE BOARD, ANSWER THE FF:a. What is a wave pulse?b. What is the source of the wavepulse?c. Describe the motion of yourhand as you create the pulse.d. Describe the motion of the pulsewith respect to the source.
A periodic wave can be regarded as a seriesof pulses. One pulse follows another in regularsuccession. Periodic Wave
BOARDWORK:Attach a colored ribbon on one partof the rope. You may use adhesivetape to fix the ribbon. Make a waveby continuously vibrating the end ofthe rope with quick up-and-downmovements of your hand. (Activity)Draw the waveform or the shape ofthe wave that you have created.
BASED ON YOUR ACTIVITY/ ILLUSTRATIONON THE BOARD, ANSWER THE FF:a. Does the wave transport thecolored ribbon from its originalposition to the end of the rope?b. Describe the vibration of thecolored ribbon. How does it move aswaves pass by? Does it move in thesame direction as the wave?c. Describe transverse waves.
BOARDWORK:Observe the waves along thecoil spring.Draw how the coil spring lookslike as you move it back-and-forth.
Attach a colored ribbon on one part of thecoil spring. You may use an adhesivetape to fix the ribbon.Ask a friend to vibrate the coil springback-and-forth while you observe themotion of the colored ribbon. Remember that the colored ribbonserves as a marker of a chosen segmentof the coil spring. (Activity)
BASED ON THE ACTIVTY, ANSWER THEFF:a. Does the wave transport thecolored ribbon from its originalposition to the end of the coil spring?b. Describe the vibration of thecolored ribbon. How does it move aswaves pass by?c. Describe longitudinal waves.
BOARDWORK:Create a wave pulse by tapping thesurface of the water with your index fingerand observe the direction of travel of thewave pulse.Tap the surface of the waterat regular intervals to create periodicwaves. (Activity)View the waves from above and draw thepattern that you see. In your drawing,mark the source of the disturbance.
BASED ON THE ACTIVTY, ANSWERTHE FF:Wait for the water to become still before youplace your paper boat on the surface. Createperiodic waves and observe what happens toyour paper boat. (Activity)a. Do the waves set the paper boat intomotion? What is required to set anobject into motion?b. If you exert more energy in creatingperiodic waves by tapping the surfacewith greater strength, how does thisaffect the movement of the paper boat?
If you were somehow able to mark individual watermolecules (you used a colored ribbon to do this) andfollow them as waves pass by, you would find thattheir paths are like those shown in the figure below. Surface Waves
a. As shown in the figure, thepassage of a wave across a surfaceof a body of water involves themotion of particles followinga___________ pattern about theiroriginal positions.b. Does the wave transport watermolecules from the source of thevibration? Support your answer usingthe shown figure.
SUMMARY FOR ACT. 11. Waves can be typified according to thedirection of motion of the vibratingparticles with respect to the direction inwhich the waves travel.a. Waves in a rope are called____________ waves because theindividual segments of the rope vibrate____________ to the direction in whichthe waves travel.
b. When each portion of a coil springis alternatively compressed andextended, ____________ waves areproduced.c. Waves on the surface of a body ofwater are a combination oftransverse and longitudinal waves.Each water molecule moves in a_______________ pattern as thewaves pass by.
2. How do we knowthat waves carryenergy?3. What happenswhen waves pass by?
ACTIVITY 2. ANATOMY OF A WAVEHOW DO YOU DESCRIBE WAVES?Most periodic waves have sinusoidalwaveforms as shown below. Thehighest point and lowest point of awave are called the crest and thetrough respectively. The amplitudeis the maximum displacement of avibrating particle on either side of itsnormal position when the wavepasses.
PARTS OF A WAVECrest- highest pointTrough- lowest pointWave length- distance between 2 wavesWave height- distance from crest totroughAmplitude- range from normal positionof wave to either side Equilibrium- no disturbance
HOW CAN YOU MEASURE THEWAVELENGTH OF A WAVE?The wavelength of a wave refersto the distance between anysuccessive identical parts of thewave. For instance, the distancefrom one crest to the next is equalto one full wavelength. In thefollowing illustration, this is givenby the interval B to F.
Identify the other intervals thatrepresent one full wavelength.
Place a basin filled with wateron top of a level table. Wait forthe water to become still.Create a vibration by regularlytapping the surface of thewater with your index finger.You would be able to see thesubsequent crest of the waterwaves.
BOARDWORK:Draw the water wavesas you see them fromthe top of the basin.Label one wavelengthin your drawing.
Increase the rate of the vibrations youcreate by tapping the surface of thewater rapidly. What happens to thewavelength of the waves?______________________________Draw the water waves as you seethem from the top of the basin.Compare it with your first drawing.
HOW DO YOU MEASURE THEFREQUENCY OF A WAVE?The frequency of a series of periodicwaves is the number of waves that pass aparticular point every one second. It isalso useful to consider the period of awave, which is the time required for onecomplete wave to pass a given point. Theperiod of each wave is = ___1___
From the identified frequencyof the observed periodicwaves, the period can becalculated. For example, if twowaves per second are passingby, each wave has a period of½ seconds.Show your table on the board.
If you increase thefrequency of vibration byjerking the end of therope at a faster rate,what happens to thewavelength?
HOW DO YOU MEASURE THE SPEED OFA WAVE?The wave speed is the distance traveledby the wave per second. =( )= ℎFrom the basic formula that applies to allperiodic waves, you can see that wavespeed, frequency and wavelength areindependent of the wave’s amplitude.
SUMMARY:1. What is the relationship between wavespeed, wavelength andfrequency?2. Suppose you observed an anchored boat torise and fall once every 4.0 seconds as waveswhose crests are 25 meters apart pass by it.a. What is the frequency of the observedwaves?b. What is the speed of the waves?