Ms. Parker's notes on April 18,2011

1. Good Afternoon! Today we will: Complete Investigation 5.3 Take notes Complete a Success Criteria Check Please do before the bell: get your lab notebook get out something to write with open your textbook to pg 508

2. Investigation 5.3 Read pg 508 – 510. Pay special attention to the two different lab set-ups we will be using. 5 min

3. Investigation 5.3 Groups of 4 Materials: clamp cup pulley fishing line mass goggles SAFETY: Do not stand with your foot under the hanging mass Goggles must be worn when string is under tension

4. Wavelength, Wave Speed, and Frequency Read pg 510 – 512 As you read, be on the look-out for: the effect of wavelength on frequency & pitch the effect of wave speed on frequency & pitch 8 min

5. Wavelength, Wave Speed, and Frequency Standing Wave: also known as a stationary wave: a wave that remains in a constant position. The length of the vibrating string in the lab determined the length of your standing wave.

6. Wavelength, Wave Speed, and Frequency If your string was 40 cm, then the wavelength of the lowest frequency standing wave was 80 cm. The length of the string is always ½ the wavelength of the lowest frequency standing wave

7. Lowest Frequency Standing Wave

8. Wavelength v Frequency What were the two ways you could get a higher frequency in today’s lab? shorten the string add tension v = fλ rearrange this formula in your notes to isolate for frequency

9. Wavelength v Frequency f = v/λ Look at your lab data for steps 4 & 5. Does your data reflect this relationship between wavelength and frequency?

10. Wavelength v Frequency f = v/λ The relationship between wavelength and frequency is inverse. In an inverse relationship, decreasing one variable (such as wavelength)increases the other (in this case, frequency)

11. Tension v Frequency Think back to the first lab we did with the string, pulley, clamp, and mass. What effect did tension have on pitch? increasing the tension increased the pitch

12. Tension v Frequency Increasing tension did not change the wavelength! So how does increased tension result in an increased pitch? increased tension on the string increases the wave speed

13. Wave Speed v Frequency f = v/λ Looking at the formula, what happens if λ is held constant while velocity is increased? frequency is increased

14. Wave Speed v Frequency f = v/λ The relationship between wave speed and frequency is a direct relationship. In a direct relationship, when one variable is increased, the other variable increases as well.