1. سرعة الموجة المستعرضة تبلغ سرعة الرياح على حبل طوله 25 متراً 50 م/ث. قوة الشد في الحبل 200 نيوتن. احسب كتلة الحبل.
أ. 0.08 كجم
B. 0.5 كجم
ج. 0.8 كجم
د. 2.0 كجم
معروف :
Length of rope (l) = 25 m
Speed of transverse wave (v) = 50 m/s
Tension force of rope (T) = 200 N
مطلوب: Mass of rope (m)
الحل:
This problem can be solved using the formula of the wave propagation formula on the rope.
والجواب الصحيح هو د.
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 …
أ. 4.5 م/ث
ب. 3.0 م/ث
ج. 2.0 م/ث
د. 1.5 م/ث
معروف :
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
مطلوب: Speed of wave (v)
الحل:
When the first wood moves up and down once, the الطول الموجي 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.
وهكذا، فإن مسافة 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)
الخامس = 4.5 م / ث
الإجابة الصحيحة هي.
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) و(2) و(3)
ج. (3) و (4)
D. (3) only
الحل:
The formula of the speed of the wave propagation on the strings:
الإجابة الصحيحة هي.
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
معروف :
التردد (f) = 50 هرتز
The wavelength (λ) = 2 meters
مطلوب: Period (T) and speed of the wave (v)
الحل:
فترة :
T = 1/f = 1/50 Hz = 0.02 seconds
The speed of wave :
v = f λ = (50 1/second)(2 meters) = 100 meters/second
الجواب الصحيح هو ب.
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.
أ. 12 مللي ثانية-1
B. 12 cm s-1
ج. 8,3 مللي ثانية-1
D. 8,3 cm s-1
معروف :
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
مطلوب: Speed of the wave propagation (V)
الحل:
Speed of the wave propagation :
v = f λ = λ / T = 10 cm / 1.2 seconds = 8.3 cm/second = 8.3 cm.s-1
والجواب الصحيح هو د.
