Embedded Files
Chapter 14: Lesson 4 - Wave Math
Chapter 14: Lesson 4 - Wave Math
Equations
Equations
It will be helpful to have your equation sheet ready. A copy of the equation sheet is under resource materials on this website and on google classroom. It can also be found HERE.
Review of the Math from Lesson 1
Review of the Math from Lesson 1
The potential energy in a spring is equal to one-half time the product of the spring constant and the square of the displacement. The unit for potential energy in a spring is Nm or Joules.
Hooke's Law can also be expressed as an equation, F=kx, where F is the force on the spring, x, is the distance that the spring stretches from the equilibrium point, and k is the spring constant. The spring constant tells us how springy or stiff a spring is. It is a constant for each spring. The units for k are N/m.
Remember that period, T, is the time that it takes for one complete revolution. In the case of a pendulum, it is one complete back and forth motion. We measure period in seconds.
The period of a simple pendulum of length, lowercase L, is shown by the equation.
Period and Frequency
Period and Frequency
Frequency is the number of complete revolutions per second. We abbreviate frequency with a fancy f, ƒ. Frequency is measured in hertz, Hz. A hertz is one vibration per second.
Frequency and period are inversely related to each other. Period equals one over frequency and frequency equals one over period.
Velocity of a Wave
Velocity of a Wave
Wave velocity is the product of the frequency and length of the wave. Since period and frequency are inversely related to each other, you can use either equation to get the speed of the wave. It just depends on what is given to you in the problem as to what equation you will use.
Check Your Understanding:
Check Your Understanding:
Click on the down arrow when you have your answer to check to see if you are correct.
Mr. Wegley attaches a slinky to the wall and begins introducing pulses with different amplitudes. Which of the two pulses (A or B) below will reach the wall first? Explain your answer.
Both pulses reach the wall at the same time. Amplitude doesn't have anything to do with the speed of a wave. Look at the equation above. Velocity depends on the wavelength and the period or the frequency.
2. Mr. Wegley then begins introducing pulses with a different wavelength. Which of the two pulses (C or D) will reach the wall first? Explain your answer.
Wave C will reach the wall first. Wave C has a longer wavelength than wave D and a larger wavelength means a larger velocity.
In Summary
In Summary
Click on this picture to take you to a summary of all the physics equations that we are using in Chapter 14!
Scan 2020-12-11 08.16.20.pdfPractice the Math!
Practice the Math!
Click here for the paper that I use in the video. As you watch this video, pause it and try the math on your own. When you have your answer, start the video and see if you are right. It is important to know where YOU make your mistakes so you can correct them for next time!
Remember there are more practice math problems under Chapter 14 Resources. Practice the math and see if your answer matches my answer.
Before the Next Class Period:
Before the Next Class Period:
Practice these Math Problems Before Class!
Practice these Math Problems Before Class!
Click on the picture to take you to the practice problems that I will be going over the next time we have class. Remember, you need to try the problems on your own to see where you make your mistakes if you want to learn how to do the math problems on your own.
You have finished Lesson 4!
You have finished Lesson 4!
Be sure to head over to google classroom and fill out the exit pass.
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