1. سرعت موج عرضی روی یک طناب ۲۵ متری، سرعت ۵۰ متر بر ثانیه است. نیروی کشش طناب ۲۰۰ نیوتن است. جرم طناب را تعیین کنید.
الف. ۱۰۰ کیلوگرم
ب. ۱۰ کیلوگرم
C. 0.8،XNUMX کیلوگرم
د. 2.0 کیلوگرم
شناخته شده:
Length of rope (l) = 25 m
Speed of transverse wave (v) = 50 m/s
Tension force of rope (T) = 200 N
تحت تعقیب: Mass of rope (m)
راه حل :
This problem can be solved using the formula of the wave propagation formula on the rope.
پاسخ صحیح D است.
2. On the surface of the lake floats two pieces of wood, the distance between them is 6 m. The waves propagate on the surface of the lake. When the first wood has moved up and down three times, the second wood just moved up and down once. If every 2 seconds both kinds of wood move up and down three times, the wave propagation is …
الف. ۱۰ متر بر ثانیه
ب. ۱۲ متر بر ثانیه
ج. ۱۵ متر بر ثانیه
د. 1.5 متر بر ثانیه
شناخته شده:
Distance between both woods (l) = 6 meters
The first timber has moved up and down three times; the second wood just moved up and down once.
Frequency (f) = 3 / 2 = 1.5 hertz
تحت تعقیب: Speed of wave (v)
راه حل :
When the first wood moves up and down once, the طول موج 1 travels to the second wood. When the first wood moves up and down twice, the wavelength 2 travels to the second wood. When the first wood moves up and down three times, the wavelength one has arrived at the second wood position, so that at the same time the second wood moves up and down once.
بنابراین فاصله between the first wood and the second wood is two wavelengths (2 λ), as shown in the picture on the side.
Distance of 1 wavelength (λ) = 6 / 2 = 3 meters
The speed of the wave propagation (v):
v = f λ = (1.5 hertz)(3 meters)
v = 4.5 متر بر ثانیه
گزینه درست الف است.
3. Factors that accelerate the propagation of waves on the strings are…
(1) extend the wire
(2) magnifying the wire mass
(3) increase the wire tension
(4) enlarge the wire size The correct statement is…
A. (1), (2), (3) and (4)
ب. (1)، (2) و (3)
ج. (3) و (4)
D. (3) only
راه حل :
The formula of the speed of the wave propagation on the strings:
گزینه درست الف است.
v = speed of the wave propagation on the strings
T = tension force of strings
μ = density of the string
m = mass of the string
l = length of string
4. On a rope propagates a wavelength rope with a frequency of 50 Hz and a wavelength of 2 m. Period and velocity of the wave are…
A. 0.02 seconds and 50 ms-1
B. 0.02 seconds and 100 ms-1
C. 0.04 seconds and 50 ms-1
D. 0.5 seconds and 100 ms-1
شناخته شده:
فرکانس (f) = 50 هرتز
The wavelength (λ) = 2 meters
تحت تعقیب: Period (T) and speed of the wave (v)
راه حل :
Period :
T = 1/f = 1/50 Hz = 0.02 seconds
The speed of wave :
v = f λ = (50 1/second)(2 meters) = 100 meters/second
پاسخ صحیح ب است.
5. A cork on the surface of water moves up and down due to the surface water waves. The time required from a crest to next crest is 1.2 seconds. If on the water surface, the distance between two crests is 10 cm, then determine the speed of the wave propagation.
الف. ۲ میلیثانیه-1
B. 12 cm s-1
ج. ۱ میلیثانیه-1
D. 8,3 cm s-1
شناخته شده:
The time required from crest to the next crest = the time interval for one wavelength = period (T) = 1.2 seconds.
Distance between two crests = distance of 1 wavelength (λ) = 10 cm
مورد نظر: Speed of the wave propagation (V)
راه حل :
Speed of the wave propagation :
v = f λ = λ / T = 10 cm / 1.2 seconds = 8.3 cm/second = 8.3 cm.s-1
پاسخ صحیح D است.
