AP Physics Homework – Waves and Media Name:
1) A 5-kg block is hung from the ceiling on a 2-m-long metal wire with a mass of 4 g. The wire is “plucked” at the very bottom, where it connects to the block. How long does it take the pulse to reach the ceiling? Hint: Calculate the tension in the wire and the mass per unit length (m) of the wire.
(Answer: 0.013 s)
2) Two tuning forks have frequencies of 275 Hz and 292 Hz. What is the beat frequency if both tuning forks are sounded simultaneously?
3) To tune middle C on a piano, a tuner hits the key and at the same time sounds a 261-Hz tuning fork. If the tuner hears 3 beats per second, what are the possible frequencies of the piano key?
4) Two strings are made of the same material and have equal tensions. String 1 is thick; string 2 is thin. Is the speed of waves on string 1 greater than, less than, or the same as the speed of waves on string 2? Explain.
5) When you tune a violin string, what causes the frequency to change? Explain.
6) On a guitar, some strings are single wires, others are wrapped with another wire to increase the linear density of the string. Which string would you expect to be used for low-frequency notes? Explain.
7) The three waves, A, B, and C, shown below, propagate on strings with equal tensions and equal mass per unit length. Rank the waves in order of increasing (a) frequency, (b) wavelength, and (c) speed. Indicate a tie where appropriate.
8) A brother and sister try to communicate with a string tied between two tin cans. If the string is 9.5 m long, has a mass of 32 g, and is pulled taut with a tension of 8.6 N, how much time does it take for a wave to travel from one end of the string to the other?
If there are 80 complete vibration waves along the string, what is the frequency of the waves?