Waves

Question 1

How does the magnitude of potential energy and the magnitude of kinetic energy vary with the displacement of a pedulum?

Answer 1

Magnitude of potential energy (PE) is the amount of stored energy and the magnitude of kinetic energy (KE) is the amount of energy in motion. As the pendulum passes through equilibrium, the magnitude of KE is maximal and the magnitude of PE is zero. As the pendulum moves away from equilibrium (displacement; either up swing or down swing), KE converts to PE. At maximal displacement, the magnitude of PE is greatest and the magnitude of KE is least.

Question 1

What is the relationship of force and the resultant wave in transverse and longitudinal waves?

Answer 1

Air molecules of a transverse wave are displaced perpendicular (90 deg) to the axis/direction of the wave. The molecules move up and down as the wave propagates left to right. With a longitudinal wave, air molecules are displaced in parallel with the wave. Air molecules move left to right and the wave also propagates left to right.

Question 2

37 Pa is equivalent to how many newtons per square meter?

Answer 2

37

Question 3

What is the derived physical quantity that defines the time-rate change in displacement?

Question 5

Why does an object traveling 60 kph have less momentum than the same object traveling 95 kph?

Answer 5

Momentum is the produce of mass and velocity (M=mc) and is directly proportional to velocity. Since mass is constant (same object), momentum is determined by velocity. The object traveling at a lower velocity will also have less momentum.

Question 6

If the period of a sinusoid is 200ms, what is the frequency?

Answer 6

5 Hz

Question 7

A sinusoid has a peak to peak amplitude of 20 sound pressure, what is the rms sound pressure?

Question 8

For pendular motion, what determines frequency and what determines amplitude?

Answer 8

For pendular motion, length determines frequency of vibration and instantaneous sound pressures determine amplitude

Question 9

Calculate the period of a sound with a frequency of 527 Hz

Answer 9

00018979 secs or 1.90 x 10^-3 secs

Question 10

Briefly discuss the benefits and drawbacks of 2 different measures of amplitude

Answer 10

1. Maximal amplitude is the max distance between a point and its equilibrium, corresponding to 90 deg and 270 deg. This is helpful because it tells us what point is the most intense, but it doesn’t give a complete picture.
2. The root mean square (rms) amplitude is the “standard deviation of all instantaneous amplitudes of a sine wave and is more helpful at providing information of what the entire stimulus is doing. RMS is most commonly used.

Question 11

Calculate Z if R = 400, Xm = 300, and Xc = 250

Answer 11

Z = sqrt (R^2 + (Xm - Xc)^2)
Z = sqrt (400^2 + (300-250))
Z = sqrt (160000+2500)
Z = sqrt (1625000)
Z = 403.11

Question 12

How does a system resonate at its natural frequency?

Answer 12

Impedance (Z) must equal resistance (R)

Question 13

Calculate the damping factor of a system with an amplitude at one peak = .89, and the next peak = .45

Answer 13

d(f) = In(A1 / A2)
d(f) = In (.89/.45)
d(f) = ln (1.978)
d(f) = .682

Question 14

Simplify: (15^2)^6

Answer 14

15^12

*multiply exponents

Question 15

Simplify: 2^5 + 2^2

Answer 15

32+4 = 36

Question 16

Rewrite these values in scientific notation: 435000, 0.00000763, and 90

Answer 16

A. 4.3 x 10^5
B. 7.63 x 10^-6
C. 9.00 x 101

Question 17

Describe interval scales

Answer 17

Interval, or linear, scales has order and degree difference that is the same at all points. It does not have a true zero point; nor is the ratio meaningful.

Example: temperature, difference between degrees are equal and zero degrees does not mean absence of temperature

Question 18

Descrie ratio scales

Answer 18

Ratio scales have meaningful differences and ratios; it also has a true zero point.

Example: weight, zero grams does mean an absence of weight

Question 19

Rewrite following logarithms in exponent form:
log(5)25
log100
log(12)144