AP Physics 12 – Class Starter
1.
Collect the Learning Outcomes for Waves from the front of the room
2.
With your neighbour review the outcomes for Section A: Wave Motion
with your neighbour
3.
Is there anything there you DON’T know how to do?
Let’s try a few review questions…
1.
Please form a group of 2-3
2.
Collect a whiteboard and pens
3.
Take out your AP Physics Equation Sheets
Question 1
A wave of length 2 m is found to have a frequency of 140 Hz. What
is the speed of the wave?
Ans: ν = λf = (2 m)(140 Hz) = 280 m/s
Question 2
A sound wave in air moves at a speed of 340 m/s. What is the
wavelength of middle C (f = 256 Hz)?
Ans: λ = ν/f = (340 m/s)/(256 Hz) = 1.33 m
Question 3
A string is tied between two walls 8 m apart. Which of the
following is not an allowed standing wavelength of the string?
Explain your answer!
a.
32 m
b.
16 m
c.
8m
d.
2m
e.
0.5 m
Question 3
A string is tied between two walls 8 m apart. Which of the
following is not an allowed standing wavelength of the string?
Explain your answer!
a.
32 m
b.
16 m
c.
8m
d.
2m
e.
0.5 m
λn = 2/n (L) can’t be larger then 16 m!
Question 4
A tube is closed at one end and open at the other. If the tube is 2
m long, what is the fundamental harmonic wavelength of the
tube?
Ans: λn = (4/n) (L) when n = 1, λ1 = 8 m
Question 5
If the closed end of the same tube is opened, and all other things
remain the same, what is the ratio of the new fundamental
frequency (both ends open) and the old fundamental frequency
(open end open and one end closed)?
fboth open
v
vn
= =
l 2L
fone open
v
vn
= =
l 4L
nn
2L = 2!
nn
4L
Question 6
One end of a horizontal strong is tied to a ring that is free to slide
along a frictionless rod. A transverse wave pulse is generated at
the other end, moves toward the ring and is reflected at the ring
and rod. Which of the following are properties of the reflected
wave?
I.
II.
III.
Its speed is greater than that of the incident pulse.
The amplitude is smaller than that of the incident pulse.
It is on the same side of the string as the incident pulse.
Question 6
One end of a horizontal strong is tied to a ring that is free to slide
along a frictionless rod. A transverse wave pulse is generated at
the other end, moves toward the ring and is reflected at the ring
and rod. Which of the following are properties of the reflected
wave?
I.
II.
III.
Its speed is greater than that of the incident pulse.
The amplitude is smaller than that of the incident pulse.
It is on the same side of the string as the incident pulse.
Question 7
A sound wave traveling through air encounters the surface of a
pond. How are the speed of the transmitted wave related to the
speed of the reflected wave?
Ans: Speed increases as density increases
Question 8
Two strings, each fixed at both ends, have different linear mass densities.
String 1 has a linear mass density μ1, string 2 has a linear mass density μ2,
and μ1 > μ2. If both strings have the same length and are under the same
tension, which of the following statements describes the relationship
between the harmonics of the strings?
I.
f1 > f2
II.
λ1 > λ2
III.
ν1 < ν 2
Question 8
Two strings, each fixed at both ends, have different linear mass densities.
String 1 has a linear mass density μ1, string 2 has a linear mass density μ2,
and μ1 > μ2. If both strings have the same length and are under the same
tension, which of the following statements describes the relationship
between the harmonics of the strings?
I.
f1 > f2
II.
λ1 > λ2 – if the length of the ropes are the same the fundamental harmonic
have to be the same!
III.
ν1 < ν 2