DAY 70

WARM-UP

**Yesterday, I came back after school, and my only pair of scissors was missing, and the slinky was on the floor. Not happy.**

1. The speed of sound in solid iron is 5,120 m/s. How long would it take a sound wave to travel through 40,075,000 m of iron?

2. Would a sound wave travel that far?

CLASSWORK

1. 070A:

**use a new sheet of paper - you'll need to turn this assignment in on Friday

Lab – Tuning Forks and Waves

Purpose – make observation about the waves formed by a tuning fork

Pre-lab Question

1. The speed of sound in room temperature air is approximately 346 m/s. Calculate the wavelength of the sound wave we heard earlier that has a frequency of 500 Hz.

Observations and Calculations

1. You will need two tuning forks, a binder (or short stack of paper to strike the tuning fork on) and a cup with water to complete the observations.
2. Strike each tuning fork on the paper. Compare the sounds that the tuning forks make and write one observation.
3. Observe the tuning fork vibrations with your eyes. Write one observation about what you see.
4. Strike the tuning fork and have it touch your ear and nose. Write one observation about what you feel.
5. Strike a tuning fork and place it in a cup of water. Write one observation about what you see.
6. Calculate the wavelength of the tuning fork using the speed of sound given in Pre-Lab question #1 and the frequency on the tuning forks.

Conclusion Questions

1. Why does sound travel faster when the air is warmer? Think: how could you use the definition of a sound wave to help explain your answer. Feel free to use the internet to help find your answer
2. Which tuning fork has a higher pitch? How do you know?
3. Compare and contrast the low frequency and high frequency tuning forks
4. How could you increase the intensity of the sound waves you produced using tuning forks?
5. Bats can use echo location to navigate and find prey. If a bat emits a sound then hears it 0.02 seconds later, how far away is the object?