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Answer:
Explanation:
Given that,
Initial angular velocity is 0
ωo=0rad/s
It has angular velocity of 11rev/sec
ωi=11rev/sec
1rev=2πrad
Then, wi=11rev/sec ×2πrad
wi=22πrad/sec
And after 30 revolution
θ=30revolution
θ=30×2πrad
θ=60πrad
Final angular velocity is
ωf=18rev/sec
ωf=18×2πrad/sec
ωf=36πrad/sec
a. Angular acceleration(α)
Then, angular acceleration is given as
wf²=wi²+2αθ
(36π)²=(22π)²+2α×60π
(36π)²-(22π)²=120πα
Then, 120πα = 8014.119
α=8014.119/120π
α=21.26 rad/s²
Let. convert to revolution /sec²
α=21.26/2π
α=3.38rev/sec
b. Time Taken to complete 30revolution
θ=60πrad
∆θ= ½(wf+wi)•t
60π=½(36π+22π)t
60π×2=58πt
Then, t=120π/58π
t=2.07seconds
c. Time to reach 11rev/sec
wf=wo+αt
22π=0+21.26t
22π=21.26t
Then, t=22π/21.26
t=3.251seconds
d. Number of revolution to get to 11rev/s
∆θ= ½(wf+wo)•t
∆θ= ½(0+11)•3.251
∆θ= ½(11)•3.251
∆θ= 17.88rev.
This question involves the concepts of echo, ultrasonic images, ultrasonic sound waves.
The process of ultrasonic images uses the "echo" property of the sound waves.
Echo is the property of the sound wave by the virtue of which the sound wave reflects back to the source of the sound after hitting a surface or an object.
Ultrasonic images are obtained from inside organs of our body. This process involves the use of ultrasonic sound waves that have a frequency greater than 20,000 Hz. These sound waves are out of the range of audible sound by the human ear. When these ultrasonic sound waves are sent in form of pulses into the human body by the use of probes, they reflect back from the tissues of different organs to the probe. The probe then records the reflection properties of these sound waves and displays them in form of an image, known as ultrasonic images.
Learn more about echo here:
brainly.com/question/14335186?referrer=searchResults
The attached picture shows the process of ultrasonic imaging.
The wavelengths of the constituent travelling waves CANNOT be 400 cm.
The given parameters:
- <em>Length of the string, L = 100 cm</em>
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The wavelengths of the constituent travelling waves is calculated as follows;
for first mode: n = 1
for second mode: n = 2
For the third mode: n = 3
For fourth mode: n = 4
Thus, we can conclude that, the wavelengths of the constituent travelling waves CANNOT be 400 cm.
The complete question is below:
A string of length 100 cm is held fixed at both ends and vibrates in a standing wave pattern. The wavelengths of the constituent travelling waves CANNOT be:
A. 400 cm
B. 200 cm
C. 100 cm
D. 67 cm
E. 50 cm
Learn more about wavelengths of travelling waves here: brainly.com/question/19249186
Refraction is said to occur when there is a change in the speed of light.
<h3>What is the angle of refraction?</h3>
We know that refraction is said to occur when there is a change in the speed of light as it travels form one medium to another.
Given that the refractive index of the rectangular glass block is 1.5. The angle of refraction can be obtained by the use of the Snell's law;
n = sin i /sinr
n = refractive index
sini = angle of incidence
sin r = angle of refraction
sinr = sini/n
sinr = sin 45/1.5
= 0.471
r = 28 degrees
b) Now;
sinr =sin 45/1.2
sinr = 0.589
r = 36 degrees
For the glass
sinr = sin 36/1.5
sin r = 0.392
r = 23 degrees
Learn more about angle of refraction:brainly.com/question/2660868
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