Examination 3

Name: —

Section:

Time: 1 hour 15 minutes

Show all of your work.

Physics 201

Fall 2010

Hans A. Schuessler

Part I: Multiple Choice Questions

Sound intensity I

Decibel

Avogadro’s number NA

Specific heat capacity c

Heat of fusion

Molar heat capacity C,

(Q = MtT

m = NA m

()Q =

(lOpts)1. What are the units of the following quantities?

= U/fr2J=

= r=

= 7 LcJ/=

2.(5 pts)

Based only on consistency of units, which of the following formulas couldnot be correct? In each case, Q is heat, m is mass, M is molar mass, and n isnumber of moles.

(a.) (3 = 10db 1og-

1

3. Which of the following is a FALSE statement?(5 pts)

(a.) In a transverse wave the particle motion is perpendicular to thevelocity vector of the wave.

(b.) Not all waves are mechanical in nature.

(c.) The speed of a wave and the speed of the vibrating particles thatconstitute the wave are different entities.

5,vaves transport energy and matter from one region to another.

(e.) A wave in which particles move back and forth in the same directionwas the wave is moving is called a longitudinal wave.

4. A string, 2.0 meters in length, is fixed at both ends and tightened until the(5 pts) wave speed is 66 m/s. What is the frequency of the standing wave shown

in Figure 12.2?

12.2

J000XXD

(a.) 99 Hz

.) 200 Hz

(c.) 300 Hz

(d.) 400Hz

2

5. A standing wave is oscillating at 270 Hz on a string, as shown in Figure(5 pts) 12.3. What is the wave speed?

FiguTe 12.3

(i110 rn/s.

(b.) 160 rn/s.

(c.) 81 rn/s.

(d.) 54 rn/s.

6. A glass flask has a volume of 900 ml at a temperature of 20°C. The flask contains(5 pts) 893 ml of mercury at an equilibrium temperature of 20°C. The temperature is

raised until the mercury reaches the 900 ml reference mark. The coefficients ofvolume expansion of mercury and glass are 18 x 10-5K1and 2.0 x 105K1,respectively. The temperature at which this occurs, in °C, is closest to:

(b.J59

(c.) 49

(d.) 64

(e.) 79

3

p

7. If you wanted to know how much the temperature of a particular piece of(5 pts) material would rise when a known amount of heat was added to it, which of

the following would be the most helpful to know?

(a.) Initial temperature

pecific heat

(c.) Density

(d.) Coefficient of linear expansion

(e.) Thermal conductivity

Part II: Short Problems

8. A certain transverse wave is described by the equation(10 pts)

y(x, t) = (6.50 mm) sin2(0060 — 0.280m)

Determine this wave’s (a) amplitude, (b) wavelength, (c) frequency, (d)speed of propagation, and (e) direction of propagation.

CoIk)5k2( -)

1’<)(b)

C)(d) ( )( /

() t

4

Standing sound waves are produced in a pipe that is 1.20 m long. For thefundamental frequency and the first two overtones, determine thelocations along the pipe (measured from the left end) of the displacementnodes it (a) the pipe is open at both ends; (b) the pipe is closed at the leftend and open at the right end?

k 4e A cJ£4-td 1. Z d-(SpkC’LA kOd. A1C%

/&

k -W P.

C) - . 7’ fs/ ; q

cidz2.a Cg5it (cI IS 1LThi 40 7&€ ,Jd.

_t• cAcs e 7)LJ- Zf cLdQ LA

>I174L

A= L =L1

,;:c d124, 72t dt1L J

L —47 C)II &id /%

(s.) 74e /& jdefrr1is-

= a 1X,4

1,’o ,\

, LL_- ô.&i

—I

9.(20 pts)

•z

___

L4uLzk4MdWe

x=O131., (O,21

U

I

:1LL

9_ AA/J L4J

10. (a) While vacationing in Europe, you feel sick and are told that you have a(10 pts) temperature of 40.2°C. Should you be concerned? What is your

temperature in °F? (b) The morning weather report in Sydney predicts ahigh temperature of 12°C. Will you need to bring a jacket? What is thistemperature in °F? (c) A friend has suggested that you go swimming in apool having water of temperature 350 K. Is this safe to do? What wouldthis temperature be on the Fahrenheit and Celsius scales?

q. T/2 )4?)_ .

b =

5 -e ciL k £V.23v1-t (ck1C/ }T=T 21s —2l

I T1S I

11. An ice-cube tray contains 0.350 kg of water at 18.0°C. How much heat(10 pts) must be removed from the water to cool it to 0.00°C and freeze it?

Express your answer in joules and in calories.

.

Q1c (cTL()

- 3.3 )/3x/ovhi-uS IS A

3 (0) (ic/ /8

6

12. (a) How much heat does it take to increase the temperature of 2.50 moles(20 pts) of an ideal monatomic gas from 25.0°C to 55.0°C if the gas is held at

constant volume? (b) How much heat is needed if the gas is diatomicrather than monatomic? (c) Sketch a pV diagram for these processes.

(v

€4-1to - /C c

Co4s1cL1t p() ( 2,

( (.3is

(

A

- ;t;I

7