Physics 365/369 Midterm, Fall 2016 Page 1 of 6
University of Calgary
Faculty of Science Midterm test
PHYSICS 365/369 LECTURE SECTIONS
November 1, 2016, 19:00- 20:30 Time: 90 minutes.
This is a closed-book exam worth a total of 16 points. Please answer all questions. Use of a
calculator is allowed.
You need the following:
1. THIS 6-PAGE QUESTION BOOKLET, which includes multiple choice exam questions and the
formula sheet (last page). THIS BOOKLET WILL NOT BE HANDED IN. Make sure this booklet
contains 6 pages (including formula sheet). If you are missing any pages, get a new booklet from the exam
supervisor.
2. A BUBBLE SHEET used to answer multiple choice questions. THIS WILL BE HANDED IN.
IMPORTANT: START by entering your ID NUMBER, NAME and COURSE ID on the bubble sheet.
Also, using a dark pen or a pencil, black out the corresponding numbers below your ID and name. DO
THIS NOW. Then wait for the Exam Supervisor to signal when to start the test.
Please note that you can leave the room at any time during the first 75 minutes of the exam. Students
remaining after 75 minutes must remain seated for the duration of the exam until permitted to leave by the
instructor.
Physics 365/369 Midterm, Fall 2016 Page 2 of 6
Questions (Total: 16 marks, 1 mark for each question)
Questions 1 – 6 are all related to the following situation:
A long string having mass density = 100 g/m is attached to an object at x=0 undergoing SHM according
to y(x=0,t) = -(10 cm)sin(20t). The string is then stretched out along the positive x axis under tension T
= 10 N. Waves launched onto the string are of the form. y(x,t) = Acos(t – kx + 0),
1. What is the wavelength of the waves?
a) 0.503 mm
b) 3.16 cm
c) 1.00 m
d) 2 m
2. What is the phase constant 0?
a) 0
b) /2
c)
d) 3/2
3. What is the maximum positive velocity of the string at x=0 ?
a) 20 m/s
b) 2 m/s
c) 10 cm/s
d) 10 m/s
4. What is the first time t 0 at which the string at x=0 reaches its maximum positive
velocity?
a) 100 ms
b) 0
c) 15.9 ms
d) 50 ms
5. At a particular instant, a point on the string has a displacement equal to half its maximum
value, and the velocity is downward (negative). What is the power being transmitted by
the string at that point and time?
a) 39.5 W
b) 4.93 W
c) 19.7 W
d) 9.89 W
Physics 365/369 Midterm, Fall 2016 Page 3 of 6
6. Sound waves from two sources meet at a point in space. At that point they each have an
identical amplitude A and are shifted in phase relative to one another by 120 degrees.
The amplitude of the superposition of the two waves is
a) equal to A
b) less than A
c) greater than A but less than 2A
d) equal to 2A
7. A particle is undergoing SHM of the form. x(t) = Acos(t + 0). Given that x(0) 0, what can be said about 0?
a) 3/2 0 has mass
density = 1 kg/m. A wave of the form. 𝑦(𝑥,𝑡) = 𝐴cos(𝑘𝑥 − 𝜔𝑡) is incident from 𝑥 <
0. If the incident angular frequency 𝜔 is 1.0 rad/s and the incident amplitude 𝐴 is 10 cm,
then the displacement of the particle at x=+1.0 m is:
a) 𝑦(𝑡) = (8.3 cm)cos(𝜔𝑡 − 0.63)
b) 𝑦(𝑡) = (8.3 cm)cos(𝜔𝑡 − 0.10)
c) 𝑦(𝑡) = (6.7 cm)cos(𝜔𝑡 − 0.63)
d) 𝑦(𝑡) = (6.7 cm)cos(𝜔𝑡 − 0.10)
Physics 365/369 Midterm, Fall 2016 Page 6 of 6
PHYS 365/369 Formula Sheet
Physical constants
Speed of light in vacuum = 3.00x108 m/s Acceleration of gravity = 9.81 m/s2
Universal gas constant = 8.314 J/K/mol Absolute zero = –273.15 °C
Mean molar mass of air = 28.8 g/mol γ = 5/3 (monatomic gas), 7/5 (diatomic gas including air)
1 atm = 1.01x105 Pa I0 = reference intensity = 10–12 W/m2
Speed of sound at 20C = 344 m/s
Formulae
v=cn nvacuum
210 IIlog10 2R4 PI maxmax ZvB kAp
I =I(0)e-ax
R2 + Z2Z1 T2 =1 21 21 ZZ ZZR 21 1ZZ Z2T
tc o skxs inA2)t,x(y
fn = vl n = n v2 L = nf 1 2t=ml
dsinq =ml msina
x = -b ± b 2 - 4 ac2a fbeat = f1 – f2
sin a + b( ) = sin a c os b + c os a sin b
c os ( a + b ) = c os a c os b - sin a sin b
sin a + sin b = 2 sin a + b
c os a - b
c os a + c os b = 2 c os a + b
c os a - b