Question

mh grade 9 bridge course scien...
course: mh grade 9 bridge... > unit 15
unit test
unit test: 60%
sound
part 2: move arms up and down twice every second. move arms the same vertical distance as in part 1.
compare the periodic waves she makes in each part of the workout.
from part 1 to part 2 of the workout, the frequency, the wavelength, and the amplitude. the energy transferred down the rope every second.

Explanation:

Step1: Define frequency

Frequency is the number of wave - cycles per second. In part 1, assume the number of arm - movements (and thus wave - cycles) per second is \(n_1\). In part 2, the number of arm - movements per second is \(n_2 = 2\) (since arms are moved up and down twice every second). If \(n_1<2\), the frequency increases.

Step2: Recall wave - speed formula

The wave - speed formula is \(v = f\lambda\), where \(v\) is wave - speed, \(f\) is frequency and \(\lambda\) is wavelength. Assuming the wave - speed \(v\) remains constant (the properties of the rope and the way it is held etc. don't change), if \(f\) increases (\(f_2>f_1\)), from \(v = f\lambda\) we get \(\lambda=\frac{v}{f}\), so the wavelength decreases.

Step3: Analyze amplitude

The amplitude is the maximum displacement from the equilibrium position. Since the arms move the same vertical distance in both parts, the amplitude remains the same.

Step4: Consider energy transfer

The energy transferred by a wave per second is proportional to the square of the amplitude and the square of the frequency (\(E\propto A^{2}f^{2}\)). Since \(A\) is constant and \(f\) increases, the energy transferred down the rope every second increases.

Answer:

Increases, Decreases, Remains the same, Increases