PHYS261- Final Review Experiment 7
Questions with Correct Answers
Experiment 7 Purpose - ANSWERSExamine the amplitude, resonant frequency,
damping time,
quality factor, and phase shift of a driven mass-and-spring oscillator.
In this lab a periodic force is applied to the cart using: (a) the sonic ranger, (b) the air
track, (c)
friction, (d) drag, (e) a spring that is attached to a speaker, (f) the function generator. -
ANSWERSA spring attached to a speaker
A mass and spring system has a resonance at fo =1.40 Hz with a full-width of
fFW=0.021 Hz.
What is the quality factor Q? - ANSWERS66.67
Q=fo/F(fw)
If the drive frequency f equals the resonance frequency fo, the phase difference θ
between the
position of the drive and the mass is (a) 0 degrees, (b) 45 degrees, (c) 60 degrees, (d)
90 degrees, (e) 180 degrees - ANSWERS90 degrees
f=0-->theta=0
f=f0-->theta=90
f>>f0-->theta=180
To what uncertainty can the drive frequency be determined in this experiment? -
ANSWERSAbout 0.00033 Hz because it can measure down to 1 mHz
Measure the resonant frequency of this system. - ANSWERSFind period (time between
two maximums), then take inverse.
Suppose that you wanted to increase the quality factor Q of the system, what could you
do? - ANSWERSThe mass could be increased.
Make a sketch, which shows how the phase depends on frequency. - ANSWERS
Make a sketch, which shows how the amplitude depends on frequency. - ANSWERS
Explain how you could measure the Q of the resonance in this system? -
ANSWERSRecord the oscillations, find f0 by finding the period and taking the inverse
(1/period), find the damping time (td, time where amplitude is 1/3 max amplitude), then
plug into equation: Q=2pif0*td/2
Questions with Correct Answers
Experiment 7 Purpose - ANSWERSExamine the amplitude, resonant frequency,
damping time,
quality factor, and phase shift of a driven mass-and-spring oscillator.
In this lab a periodic force is applied to the cart using: (a) the sonic ranger, (b) the air
track, (c)
friction, (d) drag, (e) a spring that is attached to a speaker, (f) the function generator. -
ANSWERSA spring attached to a speaker
A mass and spring system has a resonance at fo =1.40 Hz with a full-width of
fFW=0.021 Hz.
What is the quality factor Q? - ANSWERS66.67
Q=fo/F(fw)
If the drive frequency f equals the resonance frequency fo, the phase difference θ
between the
position of the drive and the mass is (a) 0 degrees, (b) 45 degrees, (c) 60 degrees, (d)
90 degrees, (e) 180 degrees - ANSWERS90 degrees
f=0-->theta=0
f=f0-->theta=90
f>>f0-->theta=180
To what uncertainty can the drive frequency be determined in this experiment? -
ANSWERSAbout 0.00033 Hz because it can measure down to 1 mHz
Measure the resonant frequency of this system. - ANSWERSFind period (time between
two maximums), then take inverse.
Suppose that you wanted to increase the quality factor Q of the system, what could you
do? - ANSWERSThe mass could be increased.
Make a sketch, which shows how the phase depends on frequency. - ANSWERS
Make a sketch, which shows how the amplitude depends on frequency. - ANSWERS
Explain how you could measure the Q of the resonance in this system? -
ANSWERSRecord the oscillations, find f0 by finding the period and taking the inverse
(1/period), find the damping time (td, time where amplitude is 1/3 max amplitude), then
plug into equation: Q=2pif0*td/2
