A string that is 3.6 m long is tied between two posts and plucked. The string produces a wave that has a frequency of 320 Hz and
1 answer:
To solve this problem it is necessary to apply the concepts related to wavelength depending on the frequency and speed. Mathematically, the wavelength can be expressed as
Where,
v = Velocity
f = Frequency,
Our values are given as
L = 3.6m
v= 192m/s
f= 320Hz
Replacing we have that
The total number of 'wavelengths' that will be in the string will be subject to the total length over the size of each of these undulations, that is,
Therefore the number of wavelengths of the wave fit on the string is 6.
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Newton's second law allows us to find that the correct answer is:
- Less than weight of the skater
Newton's second law states that the net force and is propositional to the mass and acceleration of the body
For these problems it is essential to set a reference system, with respect to which to carry out the measurements, in this case we set a coordinate system with the x axis parallel to the plane and positive in the direction of movement and the y axis perpendicular to the plane.
In the attachment we can see a free-body diagram of the problem, let's work each axis separately
x-axis
Wₓ -fr = m a
y-axis
N - = 0
N =
Where Wₓ and W_y are the components of the weight, fr the friction force that opposes the movement, m the mass and the acceleration of the body
let's use trigonometry to find the components of the weight
cos θ =
sin θ =
= W cos θ
Wₓ = W sin θ
we substitute
N = mg cos θ
From this equation we can see that the normal is less than the weight of the body.
In conclusion using Newton's second law we find that the correct answer is:
- Less than th weight of the skater
Learn more about Newton's second law here:
