Physic 203 - Spring 2006 - Quiz1
04/04/06
Name:
ID:
NOTE: cross answer e) when none of the given answers are correct
1 a) b) c) d) e)
3 a) b) c) d) e)
5 a) b) c) d) e)
7 a) b) c) d) e)
2 a) b) c) d) e)
4 a) b) c) d) e)
6 a) b) c) d) e)
8 a) b) c) d) e)
9 a) b) c) d) e) 10 a) b) c) d) e)
11), 12), 13) give an answer/explain (extra credit, 1 point each)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) If your heart is beating at 76.0 beats per minute, what is the frequency of your heart's oscillations?
A) 4560 Hz B) 1450 Hz C) 3.98 Hz D) 1.27 Hz
Answer: D
2) The position of a mass that is oscillating on a spring is given by x = (17.4 cm) cos[(5.46 s-1) t ]. What is the period of this motion?
A) 1.74 s B) 0.314 s C) 0.869 s D) 1.15 s
Answer: D
3) A sewing machine needle moves up and down in simple harmonic motion with an amplitude of 1.27 cm and a frequency of 2.55 Hz. How long does it take it to travel 11.43 cm?
A) 1.76 s B) 3.53 s C) 0.882 s D) 2.65 s
Answer: C
4) A sewing machine needle moves up and down in simple harmonic motion with an amplitude of 1.27 cm and a frequency of 2.55 Hz. What is the maximum acceleration of the needle?
A) 326 cm/s2 B) 8.26 cm/s2 C) 16.5 cm/s2 D) 163 cm/s2
Answer: A
5) A mass of 0.150 kg is attached to a spring with a force constant of 3.58 N/m and undergoes simple harmonic oscillations. What is the period of the oscillations?
A) 2.57 s B) 0.527 s C) 1.29 s D) 0.263 s
Answer: C
6) An 85.0-kg man climbs onto a 900-kg car with worn out shock absorbers and whose springs have an effective force constant of 125 kN/m. As he drives along, he hits a bump, and this starts the car oscillating with simple harmonic motion. What is the smallest amplitude of the oscillations that will cause him to bounce from his seat?
A) 7.73 cm B) 8.42 cm C) 8.95 cm D) 7.06 cm
Answer: A
7) A mass of 1.53 kg is attached to a spring and the system is undergoing simple harmonic oscillations with a frequency of 1.95 Hz and an amplitude of 7.50 cm. What is the total mechanical energy of the system?
A) 0.844 J B) 0.955 J C) 0.633 J D) 0.646 J
Answer: D
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8) A mass of 1.53 kg is attached to a spring and the system is undergoing simple harmonic oscillations with a frequency of 1.95 Hz and an amplitude of 7.50 cm. What is the speed of the mass when it is 3.00 cm from its equilibrium position?
A) 0.842 m/s B) 0.0368 m/s C) 0.551 m/s D) 0.919 m/s
Answer: A
9) A mass of 500 g is resting on a vertical spring with a force constant of 55.0 N/m. A mass of 250 g is dropped from a height of 12.0 cm onto the larger mass and sticks to it. What is the amplitude of the resulting oscillations?
A) 5.97 cm B) 11.4 cm C) 9.90 cm D) 4.71 cm
Answer: A
10) A spring with a force constant of 1.50 N/m is attached to a mass of 130 g. The system has a damping constant of
0.0220 Ns/m. How long does it take the amplitude of the oscillations to decrease from 10.0 mm to 5.00 mm?
A) 12.5 s B) 8.19 s C) 4.10 s D) 6.25 s
Answer: B
SHORT ANSWER
11) A very long "simple" pendulum requires a large massive bob to keep the cable holding it taut. Since the bob is no longer a point mass, the pendulum is actually a physical pendulum. If the distance between the support point and the center of the spherical bob is L , the radius of the bob is R , and the mass of the bob is M , the moment of inertia about the pivot is given by I = ML 2 +2 MR 2/5. What is the ratio of the period of this pendulum to the period of one that has R = 0 m?
Answer: [1 + 2( R / L )2/5]1/2
12) In designing buildings to be erected in an area prone to earthquakes, what relationship should the designer try to achieve between the natural frequencies of the building and the typical earthquake frequencies?
Answer: If possible, the natural frequencies of the building should be much smaller than the typical earthquake frequencies; this will minimize the amplitude of the oscillations of the building.
13) A child and an adult are walking. Their legs swing like physical pendulums and both swing through the same maximum angle. The adult is 1.5 times as tall as the child, and all their dimensions are scaled proportionately.
They also have the same mass per unit volume. If the walking speed of the adult is 1.3 m/s, what is the walking speed of the child?
Answer: 1.1 m/s
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