Answer:
The frequency heard is 576.78 Hz
Explanation:
The Doppler effect is defined as the apparent frequency change of a wave produced by the relative movement of the source with respect to its observer. In other words, this effect is the change in the perceived frequency of any wave motion when the sender and receiver, or observer, move relative to each other.
This is what happens in the first part of this problem, where the sender is train A and the receiver is train B. They are both moving in opposite directions. In this case, where both are in motion, the frequency perceived by the receiver will increase when receiver and transmitter increase their separation distance and will decrease whenever the separation distance between them is reduced. The following expression is considered the general case of the Doppler effect:
[tex]f'=f*\frac{v+-vR}{v+-vE}[/tex]
Where:
f ', f: Frequency perceived by the receiver and frequency emitted by the issuer respectively. Its unit of measurement in the International System (S.I.) is the hertz (Hz), which is the inverse unit of the second (1 Hz = 1 s-1)
v: Velocity of propagation of the wave in the medium. It is constant and depends on the characteristics of the medium. In this case, the speed of sound in air is considered to be 343 m / s
vR, vE: Speed of the receiver and the emitter respectively. Its unit of measure in the S.I. is the m / s
±, ∓:
We will use the + sign:
In the numerator if the receiver approaches the emitter In the denominator if the emitter moves away from the receiverWe will use the sign -:
In the numerator if the receiver moves away from the emitter In the denominator if the emitter approaches the receiverIn this case you are in a car traveling at 20 m/s and an ambulance is behind you traveling 35 m/s in the same direction.
In this case the receiver, you in the car, moves away from the emitter, while the emitter, the ambulance, approaches the receiver behind you in the same direction. So the frequency is calculated by the expression:
[tex]f'=f*\frac{v-vR}{v-vE}[/tex]
Being:
f= 550 Hzv=343 m/svR= 20 m/svE= 35 m/sand replacing:
[tex]f'=550 Hz*\frac{343 m/s-20 m/s}{343 m/s-35 m/s}[/tex]
you get:
f'= 576.78 Hz
The frequency heard is 576.78 Hz
someone help please !!
Answer:
c.
is the answer please brainliest
I NEED HELP
The average kinetic energy of the particles of two pieces of iron at the same temperature and mass would be __________.
Question 1 options:
Different
The same
Not equivilent
With in 500 degrees of eachother
Answer:
the answer is different
Explanation:
i took the test
A rocket sled accelerates forward from 10 m/s to 50 m/s in 2 seconds. What is the acceleration of the sled?
Answer:
Explanation:
Use kinematics equations
You have Vi=10m/s and Vf=50m/s and t=2s
Use equation Vf=Vo+at 50=10+a(2)
50=10+2a
40=2a
a=20 m/s^2
What is the object’s average acceleration between 0.0 s and 5.0 s?
ANSWER FAST! PLEASEE
Answer:
[tex]2.5[/tex]
Explanation:
[tex]0.0+5.0=5.0[/tex]
[tex]\frac{5}{2} =2.5[/tex]
hope this helps!!!!!!!!!!
which of the following is an example of potential energy:
(choose 2)
- a fire
- a book standing still on a shelf in the library
- a printer that is not connected
- your cellphone, when you make a call to someone
Answer:
fire is a potential energy
Two rocks of masses 5 kg and 10 kg a dropped from rest from a height of 20 m above ground. Ignore all friction and air resistance. Just before
they hit the ground, which statement is true about the rocks?
(A) The value for the acceleration of the 5 kg rock is the same as the value for the 10 kg rock, but their velocity values are different.
(B) The values for the acceleration and velocity of the 5 kg rock are greater than the values for the 10 kg rock.
(C) The values for the acceleration and velocity of the 5 kg rock are less than the values for the 10 kg rock.
(D) The values for the acceleration and velocity of the 5 kg rock are the same as the values for the 10 kg rock.
Answer:
D
Explanation:
F=ma
F of 5 kg rock = 49N
F of 10 kg rock = 98 N
Divide by respective masses to get acceleration, and of course you will get 9.8 m/s^2 for both.
Now, use potential energy equals kinetic energy. mgh=(1/2)mv^2 mass cancels out of the equation, since it's on both sides, so we can stop right there. We have algebraically determined that mass does not affect acceleration or velocity!
Hope this helped.
An object is moving to the right at a constant velocity. What will happen if a
force of 20 N starts acting on it in the opposite direction?
А The object's velocity will increase.
B
The object's velocity will decrease.
с
The object will come to a stop.
D
The object will move at the same velocity.
The graph shows the amplitude of a passing wave over time in seconds (s) What is the approximate frequency of the wave shown? A. 6 Hz B. 0.2 0.4 Hz
Answer:
0.2 I took the test
Explanation:
I took the test
The time period of the whole wave cycle is 6 seconds but the time period of one complete wave is about 4 seconds here. The inverse of this time period is the frequency, that is 0.2 Hz.
What is frequency ?Frequency by definition is the number of events per unit time. Frequency of a wave is the number of wave cycles in one second. It is the inverse of the time period.
Frequency is directly related to the energy of the wave. As the frequency increases, energy of the wave also increases. In the given graph the wave cycle is given for a time of 6 seconds.
The time period for one complete wave is 4 second from the graph.
thus, T = 4 s
v = 1/T
= 1/4 = 0.2 s⁻¹ or 0.2 Hz
Therefore, the frequency of the wave shown, is 0.2 Hz.
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which material would you select to replace broken handle of electric kettle
please will mark as brainlist
Answer:
hot glue
Explanation:
-insert the hot melt cylinder into the gun and wait until it heats up;
-gently apply a layer of substance to the crack;
-spread the hot glue in a thin layer over the surface;
-wait until it freezes.
What's a real-life example of Newton's Second Law?
pls help, i really dw fail :(
Answer:
Using the Newton equation
V²=U² +2as
Given; V=9.2m/s U = 0m/s( because it starts from rest)
S=26.2m.
9.2²=0²+2(26.2)a
a =9.2²/2(26.2)
a=84.6/52.4
a=1.60m/s²
Answer:
2.A
3.D
Explanation:
HOPE THIS HELPS!! :)
I got stuck on this question
Answer it 2n
Explanation:
A power source of 6.0 V is attached to the ends of a
capacitor. The charge is 12 C.
An archer uses 2000J of energy to pull a bow string 0.15m. What is the force constant (k) of the bow string?
The spring constant of the given bow spring is equal to 1.77 × 10⁵ N/m.
What is Hooke's law?Hooke's law can be described as a law that states that the force (F) required to extend or compress a spring by displacement linearly with respect to that displacement along a straight line.
The spring force can be represented in the form of an equation:
F = -kx
where k is a spring constant of the spring and x is the deformation of the spring. The negative sign shows that force is restoring force.
The energy that can be stored in the spring when it is stretched is given by:
E = (1/2)kx²
Given, the energy stored in the spring when it is stretched, E = 1000J
The distance by which the bow spring is stretched, x = 0.15 m
2000 = (1/2) × k (0.15)²
k = 1.77 × 10⁵ N/m
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physics help me pleaseee
Answer:
letter e.
Explanation:
because i know its not too deep
A wave frequency of 440 Hz travels through a medium at 343 m/s. Calculate the wavelength
for this wave.
150,920 m
1.28 m
97 m
0.078 m
Answer:
0.78 m
Explanation:
us the formula
speed = frequency x wavelength
343 = 440 x wavelength
343 / 440 = wavelength
wavelength = 0.78 m
I think the last option, you wrote wrongly, it is supposed to be 0.78 not 0.078 .
if you think I am wrong please do tell me, I will redo this.
hope this helps
32. Increasing the amplitude of a sound wave produces a
sound with
1. lower speed
2. higher pitch
3: shorter wavelength
4. greater loudness
Answer:
4
Explanation:
because amplitude of a sound wave is related to loudness of the sound, so the higher the amplitude, the louder the sound
hope this helps
Please help!!!!!!!!
Answer:
Option C. 83.8 J
Explanation:
From the question given above, the following data were obtained:
Mass (m) of object = 2 Kg
Velocity (v) of the object = 5 m/s
Height (h) = 3 m
Mechanical energy =.?
Next, we shall determine the kinetic energy of the object. This can be obtained as shown below:
Mass (m) of object = 2 Kg
Velocity (v) of the object = 5 m/s
Kinetic energy (KE) =?
KE = ½mv²
KE = ½ × 2 × 5²
KE = 1 × 25
KE = 25 J
Next, we shall determine the potential energy of the object. This can be obtained as shown below:
Mass (m) of object = 2 Kg
Height (h) = 3 m
Acceleration due to gravity (g) = 9.8 m/s²
Potential energy (PE) =.?
PE = mgh
PE = 2 × 9.8 × 3
PE = 58.8 J
Finally, we shall determine the mechanical energy of the object. This can be obtained as shown below:
Kinetic energy (KE) = 25 J
Potential energy (PE) = 58.8 J
Mechanical energy =?
Mechanical energy = KE + PE
Mechanical energy = 25 + 58.8
Mechanical energy = 83.8 J
Elements with positive valences usually ______ electrons
A. Donate
B. Accept
C. Have no
D. Create
What happens when a pebble lying on the ground is kicked?
A. Energy is completely lost.
B. Energy is created.
C. Energy is destroyed.
D. Energy is transferred.
Answer:
I'm 100% sure it's D. but if it isn't, sorry :(
3 Describe the two possible things that can happen if a charged object is brought near
another charged object,
4 Give one example of a balloon repelling another object, Explain why the balloon repelled
the object
Answer:
For two objects of charges q1 and q2, that are separated by a distance R, the force that each object suffers is given by the Coulomb's:
F = k*q1*q2/R^2
If both charges have the same sign, then we have a positive force, which means that the objects are "pushing" each other, then this is a repulsive force.
If instead, each object has a charge with a different sign, the force will be negative, then the objects will be pulling each other, and the force is an attractive force.
a) Whit this in mind, the two possible things that can happen if a charged object is near another charged object are:
The objects repel each other, which happens when both objects have charges with the same sign.
The objects attract each other, which happens when the objects have charges with a different sign.
b) A charged balloon most probably has a static charge (the type of charge that can be obtained by rubbing the balloon with a piece of cloth), which means that it has extra electrons, and we know that electrons have a negative charge, then we can assume that this balloon has a negative charge.
Then if we put another charged balloon (also with static charge) near our original balloon they will repel each other, this happens because both balloons have a negative charge.
How is a mixture different from a compound?
Answer:
MIXTURE
1 In a mixture two or more substances are mixed together (elements or compounds)
2Therd is no fixed proportion of the constituents
3 The mixture may or may not be homogenous
4 There is no chemical reaction between the constituent substances
5 There cannot be a chemical formula for a mixture
6 Heat or any other type of energy is not required or released during the formation of a mixture
7 The constituents can be separated using simple physical processes
8 The properties of the constituents are retaied
COMPOUND
1 Two or more elements form a compound
2 The constituent elements combine in a definite proportion to form a compound
3 The elements are in a definite proportion in any part or fraction of the compound
4 There is a chemical reaction in the formation of a compound
5 A compound has always a chemical formula for a compound
6 Heat orany other energy is often required for the formation of a compound or released during the formation of a compound
7 The constituent elements can't be separated using simple physical processes in case of a compound
8 The properties of the constituent elements are not retained in the compound
The brakes of a 2000 kg car apply a force of 250 N to slow down a car as it comes off of an exit ramp. What is the acceleration of the car?
Which of the following instruments measures time most accurately?
a. Sundial
b. quartz watch
c. pendulum clock
d. watch with balance wheel
Answer:
b) Quartz Clock
Explanation:
It's is a very type of clock which uses the vibration of quartz crystals to measure time accurately
If a ball that is 10 meters above the ground is thrown horizontally at 5.51 meters per second. a. how long will it take for the ball to hit the ground? b. how far will the ball travel in the horizontal direction before it hits the ground?
Answer:
a. t = 1.43 s
b. d = 7.88 m
Explanation:
a. The time of flight can be found using the following equation:
[tex] y_{f} = y_{0} + v_{0_{y}}t - \frac{1}{2}gt^{2} [/tex]
Where:
[tex]y_{f}[/tex]: is the final height = -10 m
[tex]y_{0}[/tex]: is the initial height = 0
[tex]v_{0_{y}}[/tex]: is the initial speed in the vertical direction = 0
g: is the acceleration due to gravity = 9.81 m/s²
By solving the above equation for "t" we have:
[tex] t = \sqrt{\frac{2y_{f}}{g}} = \sqrt{\frac{2*10 m}{9.81 m/s^{2}}} = 1.43 s [/tex]
Hence, the ball will hit the ground in 1.43 s.
b. The distance in the horizontal direction can be found as follows:
[tex] x_{f} = x_{0} + v_{0}t + \frac{1}{2}at^{2} [/tex]
Where:
x₀: is the initial position in the horizontal direction = 0
a: is the acceleration in the horizontal direction = 0 (it is moving at constant speed)
[tex] x_{f} = 5.51 m/s*1.43 s = 7.88 m [/tex]
Therefore, the ball will travel 7.88 m before it hits the ground.
I hope it helps you!
A piece of wire length 30cm and cross sectional area of 0.5mm^2 has a resistance of 5ohms at 20°c. It is then heated to a temperature of 150°c. Calculate it's resistivity at 20°c
Answer:
8.333*10^-6 ohms
Explanation:
Resistivity of a material is expressed as;
p = RA/l
R is the resistance of the material
A is the cross sectional area
l is the length of the material
Given
R = 5 ohms
A = 0.5mm^2
A = 5 * 10^-7m^2
l = 30cm = 0.3m
Substitute into the formula;
p = (5 * 5 * 10^-7m^2)/0.3
p = 25 * 10^-7/0.3
p = 0.0000025/0.3
p = 8.333*10^-6
Hence its resistivity at 20 degrees Celsius is 8.333*10^-6 ohms
As a cold air mass advances on a warm air mass, what usually comes before it?
Answer: A cold front occurs when a cold air mass advances into a region occupied by a warm air mass. If the boundary between the cold and warm air masses doesn't move, it is called a stationary front.
Explanation: Two types of occluded front exist: the warm-type and the cold-type. They’re distinguished by the relative temperatures of the air mass ahead of the occlusion – in other words, the air mass ahead of the original warm front – and the air mass behind the cold front. If the air behind the cold front is colder than the air ahead of the occlusion, it shoves beneath that air (because it’s denser) to form a cold-type occluded front. If the air behind the cold front is warmer than the air ahead, it rides over it to form a warm-type occluded front – which appears to be the more common case. In either situation, the lighter warm air representing the air mass originally between the warm and cold fronts sits above the boundary between the two cooler air masses.
Hope this helps!!
What do the arrows in this photograph represent?
A. Gravity and air resistance
B. An action-reaction force pair
C. A pair of unbalanced forces at work
D. Friction and air resistance
Answer: B An action-reaction force pair
Explanation: Took the exam
The arrows in this photograph represent: An action-reaction force pair. Hence, option (B) is correct.
What is action-reaction force pair?When two bodies interact, they exert an equal and opposite force on one another in accordance with Newton's third law of motion. Action-reaction forces are made up of these forces.
"When one body exerts a force on the other body, the first body experiences a force that is equal in magnitude in the opposite direction of the force which is exerted," according to Newton's third law of motion.
According to the above assertion, there are always two forces operating on the objects involved in an interaction. The forces are of identical magnitude, but the direction of the force acting on the first object is different from the direction acting on the second.
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Which location, 23 degrees or 48 degrees would experience the same earthquake at stronger intensity?Explain why.
Answer:
48 degress
Explanation:
An earthquake causes many different intensities of shaking in the area of the epicenter where it occurs. So the intensity of an earthquake will vary depending on where you are. Sometimes earthquakes are referred to by the maximum intensity they produce. In the United States, we use the Modified Mercalli Scale. Earthquake intensity is a ranking based on the observed effects of an earthquake in each particular place. Therefore, each earthquake produces a range of intensity values, ranging from highest in the epicenter area to zero at a distance from the epicenter.
What type of Circuit do they use in a home? WHY ? (Simple circuit / Parallel circuit / Series circuit)
Answer:
Parallel Circuits
Explanation:
Loads can be operated on their own. If you had a series circuit, adding another light would dim the rest!