PHY 131X - WORKSHEET Session 3 J

Exam 3 Review

I. What is the frequency of the wave shown in the figure? (El) .

A) 0.5 Hz.

BJ 1 Hz. C) 2 Hz.

D) 4 Hz.

E) lt_cannot be determined from the given information:

t -:=.. I IT '.:. 1/2 - - 0 · '5ti2 -2 • A 0. 39-kg block on a horizontal frictionless surface is attached to an ideal spring whose force

constant (spring constant) is 570 N/m. The block is pulled from its equilibrium position at x =

0.000m to a displacementx = +0.080 m and is released from rest. The block then executes

simple harmonic motion along the horizontal x-axis. When the position of the block is x = 0.057

m, its kinetic energy is closest to (El) "- ·:S1-0~ ""'~ 0 . , I:\. \::u., . A) 0.90J . I<\= '=-- 1/ 2.. ~ \J 'L J

B) 0.84J. [~ --;... 0 · 0'5VV'\

C) 0.95J.

D) 1.0J. '1'~ ,;. - A \,\J ~ JS) ( w t-) E) 1.1 J

'?C. :::. Ac o-:,(wt} 'l ·\'°':::. M \AJ

0-05'1' = o·o'1!c,sC'?.1l ·1">*} w ~ 1~ .f-:.. O·O t.0~:"> J-;. ,.(o,0S)Ci~-'2~)5'.t)(w~-'J1.Ql)

:;:::::.... - l·l "'- 5,vds

3. The position of an object that is oscillating on a spring is given '6y the equation x = (18.3 cm)

cos[(2.35 s-l)t]. What is the frequency of this motion? (E3) . _ t "\

A) 0.426 Hz. X := t.,ft;• 't") ('1. ~ )

B) 0.213 Hz.

C) 1.18Hz.

D) 0.374 Hz. f) It cannot be determined from the given information.

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4 · The int . I A h

d. ensity of the waves from a point source at a distanced from the source is · t w at

•stance fr h -

A) d/2 om t e sources is the intensity equal to 21? E2 ,

B) d/-y2 -=,l~)

C) d/4 I, -;:::. P/ -;:: D ~ _e_ D) d/8 A 'fn-f,~ <t fi d/ E) d

,.JI~,;) k'J ol'l.- ➔ T,a.;::,. U t-c: - ~\t'l) cs,= ~d,'3

5 . The frequency of th . . . .

H . e standing wave in a pipe (both ends open) shown in the right figure ts 302

z. What 1s the fu d A) 50.5 Hz n amental frequency of the pipe? E2

B) 101 Hz iiiiii~======::i;iiii~=======:~ij°i

C) 151 Hz

D) 252 Hz

E) 303 Hz

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6. If the intensity level of one trombone is 70 dB, calculate a reasonable estimate for the intensitv

level of 76 trombones all playing simultaneously in the same place? E3

A) 146 dB

B) 89 dB

C) 70 dB

D) 76 dB

E) 82 dB

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r 7. A standing Wave is . speed? oscillating at 950 H .

· El --!_ on a string, as shown in the figure. What is the wave

A) 380 rn/s

B) 570 rn/s -\-lurcl ~o.,r,Mo" \<. C) 290 rn/s

D) 190 rn/s

E) 950 rn/s A-=- 2 k.,

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8· A rope with a total mass of 25.0 kg is tied to a tree on one side of a 125-m wide ravine. You are

pulling on the other end of the rope with a force of 415 N. If you pluck the rope at your end,

how long will it take the pulse to travel across the ravine to the tree? El -

A)5.0s _ L ~""'

B)0.060s 1'1\:::-t ")r-dv ~ :? \

C)15.7s -~ c.r\ D~ D) 17.2 s I - ;__ 1 · -E) 2.74s

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9. A car approaches you ~ ~ o~tant-s-1:>eed, sounding its horn, and you hear a frequency of 76 Hz.

After the car goes by, you hear a frequ~ncy of 65 Hz. What is the frequency of the~

emitted by the horn? The speed of sound in the air is 343 m/s. E3

A) 68 Hz

B) 69 Hz

C) 70 Hz

D) 71 Hz

E) 72 Hz

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. . toward the center of b th pointing

. nd of a gymnasium, 0 . hase. An observer at the

10. Two loudspeakers are placed at either e m·,t 266-HZ sound ,n P d ·ther speaker must . h peakers e f t war e1

the gym and eg!:!_[distant from it. T es ·ve interference. How ar O

d of sound in air is 343 center of the gym experiences construct• . . t rference? The spee

. d truct1ve 1n e the observer walk t~xperience es il - d,__i. 'l-bh i,\ 'L

m/s. E3 "l.f>(l H 'L · - ~ ?' A)0.888m F ~\<::: 5'2.. B)O.lllm ~l • C) 0.644m - ~ ~ D) 0.211 m o<.c E) 0.322m

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I ~('. ~ C.\-C..7__ ~'l,.?C.. -=£_ 1,_-,.?t. - - f 36 ~ 11. Two in-phase loudspeakers are some distance apart. They emit sound with a frequency

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. 1. . • • the two speakers w,t a Hz. A microphone is moved between the speakers along the me iommg

. d f sound in air is 343 constant speed of 1.60 m/s. What b~cy 1s observed? The spee 0

m/s. E3 5~6 t\ 2. r--. <. " ,.,..(~ ~ 5:,6 ~ 'l..

A)S.00Hz S\ ,~ q,~ \ . ) 8)6.00Hz \ ~ \ \:,eJ\- ""\f'-\ - t-., .

E) 9.00Hz to '1...

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~ 2. A 4.0-kg cylinder of solid iron is supported by a string while submerged in water. What is the

tension in the string? The density of iron is 7860 kg/m3 and.that of water is 1000 kg/m3. E3 A) 2.5 N

B) 20 N C) 24 N

D) 34 N

E) 40 N

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13. A cubical b ox 25 Deni box is 109.40 kPa a ;a: each side i~immersed in a fluid. The pressure at the top surface of the the fluid? E2 n t e pressure on the bottom surface is 112.00 kPa. What is the density of

A) 1000 kg/m3 B) 1030 kg/m3

~3 D) 1090 kg/m3 E) 1120 kg/m3

Ps ~~T +20~ 112.Jcl'O? ~ wq.4,\\0~ ~ y(c,"J1) lo-1.5")

~-=- 10~0 -l't~ll""~_I 0 14· · Object 1 has three times the~ pecific heat capacity and four times the mass of Object 2. The

two objects are heated from the same initial temperature, TO, to the same final temperature Tf.

During this process, if Object 1 absorbs heat a, the amount of heat absorbed by Object 2 will be

(E2)

A) 12Q. ""' l -=:.. 4 M J. L\'f ~ If- ·-·-\.:, ::... ~ 8)6Q. { C)(3/4)Q. C\-:.. ~Ct.. '<y\-:.. MtC.14 \

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15. A styrofoam sphere of radius R has a density p. You now carefully compress the sphere so its

radius is R/2. What is the density of the compressed sphere?

A) 2 p

B) 4p

C)p./B

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. . length? Aluminum ·c What is its new

16. An aluminum rod 17.400 cm long at 20•c is heated to 100 . h-J (t,._ ~

has a linear expan~cient of 25 x 10-6 K-1. (El) lo -::- \'I;\ C U A) 0.0348 cm B) 17.435cm

C) 17.365cm

D)0.34Bcm

E) 3.48cm

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co • . -a -,, I{: q c,,..," lf- -;.. fl L ~ Lv1 ;:::... _ D . O b\Lg +-- ~r--1'

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• 1 P = 925 kg/m3 ) is flowing through a pipeline at a constant speed w en . f the

r I b . . sert,onal area o -ver ica end m the pipe raising it 4.0 mas shown in the figure. The cross= . . h

. d . P . t Band Point A int e pipe oes not change. What is the difference in pressure (PB - PA) at oin

portions of the pipe before and after the rise? (E3)

A) -1.2x104 Pa

B)-3.6x104Pa

C) 4.2x104 Pa

D) 3.6x104 Pa

E) 1.2x104 Pa

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Point B

Point A

,..... .. ~- b ",o pe, 18. How much heat is requfred to change 456 g of ice at-25.0"C into water at 25.0"C? The specific

heat of ice is 2090 .1L.(kg K), specific heat of water 4186J/(kg K), and the latent heat of fusion of

water-is 33.5 x 104 J/kg. (E3)

A) 224 kJ ,- ~ z,s"C ~

B) 153 kl (I) j C.0.. -=, () C _. C) 112 kJ ~

D)71.5kJ

(!J°C E) 72.5kJ oc..

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19. A 117 g lead ball is dro e ground is totally in 1

• rom a height of 7 .62 m. The collision between the ball and th pped from rest f -find its change in t e ast"· Assuming the ball' s ~netlc ene<OV goes Into heating the ball,

1.17 °c · e spec1f1c heat of lead is 128 J /{~g,· 1(:-) tU)--. A) emperature Th ..

B) 0.584 •c 0, ,'ti ~ "" <-j?r _ 'O

02 ✓ ">- .,.. C) 0.292 °( 1 4' D)0.146°C ~

::: £> · \--~ E) 2.34 °( \{ l ,o-D ~ /Jl<S cc. \cf- ~ k i W- 'k-1'";>- ,.-1. ...

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20 · A runner generates power 1260 W of thermal energy. If this heat has to be removed 0 -'il <I-~ J evaporation, how much water does this runner lose in 15 minutes of running? 1he latent heat ol

vaporization of water is 22.6 x 105 J/kg.

A) 50g

B) 500 g

C) 35 g D) 350 g E) 40g

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