PHYSICS 1 - CHAPTERS 14 -17 LECTURE REVIEW ******PLEASE ANSWER AS MANY QUESTIONS

Question

PHYSICS 1 - CHAPTERS 14 -17 LECTURE REVIEW

******PLEASE ANSWER AS MANY QUESTIONS AS POSSIBLE. I ONLY HAVE 5 QUESTIONS LEFT THIS MONTH.

PLEASE PROVIDE DETAILED SOLUTIONS AND EXPLANATIONS TO AS MANY QUESTIONS AS POSSIBLE.

***NOTE: FOR 1-8, MAKE SURE YOUR ANSWERS TO EACH QUESTION MATCH THE ANSWERS IN PARENTHESIS AT THE END OF EACH QUESTION.

5) A mass is oscillating on a spring with a period of 4.60 s. At t = 0 s the mass has zero speed and is at x = 8.30cm.

(a)   What is the value of t the first time after t = 0 s that that the mass is at x = 4.15 cm?

(b) What is its acceleration at t = 2.50 s? [(a) 0.767 s (b) 14.9 cm/s^(2) ]

6) A factory siren indicating the end of a shift has a frequency of 90.0 Hz.
(a) What frequency is perceived by the occupant of a car traveling towards the factory at 25 m/s?

(b) What frequency is perceived by the occupant of a car traveling away from the factory at 30 m/s? [a) 97 Hz(b) 73 Hz ]

7)  One of the harmonics of a column of air open at one end and closed at the other has a frequency of 448 Hz and the next higher harmonic has a frequency of 576 Hz. What is the fundamental frequency of the air column?[64 Hz]

8) A 50.0-g sample of a material at 80.0°C is dropped into a calorimeter containing 100.0 g of water at 20.0°C. When the mixture reaches thermal equilibrium, it is at a temperature 24.0°C. If heat transfer to the walls of the calorimeter is negligible, what is the specific heat of the material? [0.143 cal/(gC°)]

CHAPTER 16 LECTURE REVIEW

9) Calculate the wave velocity of theocean wave if the distance betweenwave crests is 10.0 m and the time fora sea gull to bob up and down is 5.00 s.

10) The wave intensity I is power per unitarea: I = P/A. The average intensity of sunlight on Earth’s surface is about 700 W/m^(2).

(a) Calculate the amount of energy thatfalls on a solar collector having an area of 0.500 m^(2) in 4.00 h.

(b) What intensity would such sunlighthave if concentrated by a magnifyingglass onto an area 200 times smaller

than its own?

11) Piano tuners use beats routinely in their work. When comparinga note with a tuning fork, they listen for beats and adjust thestring until the beats go away (to zero frequency). If a tuning forkhas a 256 Hz frequency and two beats per second are heard,what is the piano note frequency?

12) Consider a string of L = 2.00 m attached to an adjustable-frequency string vibrator as shown. The waves produced bythe vibrator travel down the string and are reflected by thefixed boundary condition at the pulley. The string, which has alinear mass density of = 0.006 kg/m, is passed over africtionless pulley of a negligible mass, and the tension isprovided by a 2.00-kg hanging mass. (a) What is the velocity ofthe waves on the string? (b) List the frequencies that the stringvibrator must be tuned to in order to produce the first threenormal modes of the standing waves.

CHAPTER 17 LECTURE REVIEW

13) Calculate the wavelengths of sounds at the extremes of theaudible range, 20 and 20,000 Hz, in 30.0°C air. (Assume thatthe frequency values are accurate to two significant figures).

14) Each factor of 10 in sound intensity corresponds to 10 dBincrease. For example, a 90 dB sound compared with a 60dB sound is 30 dB greater, or three factors of 10 (that is,103 times) as intense. Another example is that if one soundis 107 as intense as another, it is 70 dB higher. Show that if one sound is twice as intense as another, it hasa sound level about 3 dB higher.

15) Two speakers are separated by 5.00 m and are being drivenby a signal generator at an unknown frequency. A student witha sound-level meter walks out 6.00 m and down 2.00 m, andfinds the first minimum intensity, as shown below. What is thefrequency supplied by the signal generator? Assume the wavespeed of sound is v = 343.00 m/s.

16) What length should a tube closed at one end have on a daywhen the air temperature, is 22.0ºC , if its fundamentalfrequency is to be 128 Hz (C below middle C)?
What is the frequency of its fourth overtone?

17) Suppose a train that has a 150-Hz horn is moving at 35.0 m/sin still air on a day when the speed of sound is 340 m/s.

(a) What frequencies are observed by a stationary person at the side of the tracks as the train approaches and after it passes?

(b) What frequency is observed by the train’s engineer traveling on the train?

PLEASE NEED ANSWERS ASAP!!!

Explanation / Answer

Q5.

part a:

let the equation of the SHM is given by

x(t)=A*cos(w*t+phi)

then speed=dx/dt=-A*w*sin(w*t+phi)

where A=amplitude

w=angular frequency=2*pi/time period=1.3659 rad/s

at t=0, speed=-A*w*sin(phi)

given speed =0 at t=0

hence phi=0

at t=0, x=8.3 cm

==>A*cos(0)=8.3 cm

==>A=8.3 cm=0.083 m

let at time t, x=4.15 cm

==>0.0415=0.083*cos(1.3659*t)

==>t=0.767 seconds

part b:

acceleration=dv/dt=-A*w^2*cos(w*t)

at t=2.5 seconds

acceleration=-0.083*1.3659^2*cos(1.3659*2.5)

=0.14911 m/s^2

=14.911 cm/s^2

Q6. using doppler effect, frequency heard by a moving observer of a sound coming from stationary source

=original frequency*(speed of sound+speed of the observer)/speed of sound

=90*(343+25)/343

=96.56 Hz

part b:

when the receiver is moving away from the source,

frequency heard by the observer=original frequency*(speed of sound-speed of the observer)/speed of sound

=90*(343-30)/343

=82.128 Hz

Q7.
let fundamental frequency=f

for open air column, only odd integral level harmonics exist.

let nth harmonic is 448 Hz.
==>(n)*f=448..(1)

n+2 th harmonic frequency=576 Hz
(n+2)*f=576...(2)

subtracting equation 1 from equation 2:

2*f=576-448

==>2*f=128

==>f=64 Hz

Q8.

as no heat is lost to the environment,

heat lost by the material=heat gained by the water

==>mass of materia*specific heat of the materia*temperature difference=mass of water*specific heat of water*temperature difference

==>0.05*specific heat of material*(80-24)=0.1*4186*(24-20)

==>specific heat of material=0.1*4186*4/(0.05*56)=598 J/(kg.degree celcius)

=598/4186 cal/(g.C)

=0.14286 cal/(g.C)

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