Answer:
20 MHz
Explanation:
Since speed of radio waves = speed of light = c and for a wave, v = fλ where v = speed of wave, f = frequency and λ = wavelength.
Given that λ = 15 m and v = c = 3 × 10⁸ m/s
f = v/λ
substituting the values of the variables into the equation, we have
f = v/λ = 3 × 10⁸ m/s ÷ 15 m
= 0.2 × 10⁸ Hz
= 2 × 10⁷ Hz
= 20 × 10⁶ Hz
= 20 MHz
without calculation explain why the vertical component of velocity v h changes from 3.5 m/s at A to 0 m/s at B
Answer:
due to gravity.
Explanation:
.............
Why do the balls react differently when you drop them together?
Explain how this increases their efficiency. Explain how this increases their efficiency. Antireflective coating causes the phase shift of the light on the interface between the air and the panel increasing the path length of the light, so the solar panel turn more light into the energy. Antireflective coating decreases the index of refraction of the solar panel, so the losses of light caused by the refraction in the panel decreases, and the efficiency of the panel increases. Antireflective coating cancels the reflection of light from the panel, so the greater part of light enters the solar panel and can be turned into the energy. Antireflective coating refracts the light falling on the panel so the light of different wavelengths falls onto the different places of the solar panel and turns into energy with increased efficiency.
Answer:
c) True. If the coating cancels the light requested by the reflection, so there is more energy to enter the cell and therefore its efficiency increases
Explanation:
This exercise asks to analyze the effect of the antireflective coating on the efficiency of solar cells.
Let's start by expressing the expression for the interference of two light beams taken at when
* the phase change introduced when passing from air to 180º film
* the wavelength change by the refractive index of the film ln = lo / n
therefore the expression for destructive interference is
2 n t = m λ
where m is an integer
with these concepts we can analyze the different statements
a) False. Phase shift does not change the wavelength of light
b) False. The refractive index of the solar cell is not affected by the refractive index of the film since the two materials do not mix.
c) True. If the coating cancels the light requested by the reflection, so there is more energy to enter the cell and therefore its efficiency increases
d) false. In solar cells the incidence is almost normal, therefore the effect of refraction (separation of colors for different angles) is very small
A billiard ball is moving in the x-direction at 30.0 cm/s and strikes another billiard ball moving in the y-direction at 40.0 cm/s. As a result of the collision, the first ball moves at 50.0 cm/s, and the second ball stops. In what final direction does the first ball move?
Answer:
53.13 °
Explanation:
In order to do this, we just need to apply the following:
tanα = Dy/Dx
Where:
Vy: speed of the ball in the y axis.
Vx: speed of the ball in the x axis.
At this point we do not need the speed of the first ball after the collision because in that moment is already heading in the direction that we are looking for. Therefore, we just need to use the innitial data to calculate the direction which the first ball will go.
According to this, then:
tanα = (40/30)
tanα = 1.3333
α = tan⁻¹(1.3333)
α = 53.13°This means that the final direction of the first ball is 53.13° and in the x axis because the starting momentum of this ball in the x axis has not dissapeared.
Hope this helps
What is the impulse of a baseball thrown with a force of 75 N when in contact with the pitcher's
hand for 0.050 seconds?
Answer:
3.75Ns
Explanation:
Given data
F= 75N
time= 0.05seconds
We know that
P=Ft
substitute
P=75*0.05
P=3.75Ns
An object moves along the x-axis. Its position is given by the equation y( X = 4t^2 - 41t+ 78 \). Find the position of the
object when it changes direction
The object changes direction when its velocity changes sign. You can get the velocity function by differentiating the position function with respect to time t :
x(t) = 4t ² - 41t + 78
→ v(t) = dx(t)/dt = 8t - 41
Solve v(t) = 0:
8t - 41 = 0
8t = 41
t = 41/8 = 5.125
Just to confirm that the velocity indeed changes sign:
• Pick any time before this one to check the sign of v :
v (0) = 8•0 - 41 = -41 < 0
• Pick any time after and check the sign again:
v (6) = 8•6 - 41 = 7 > 0
Now just find the position at this time:
x (5.125) = -433/16 = -27.0625
which means the object is 27.0625 units on the negative x-axis.
You can also do this without calculus by completing the square in the position function:
4t ² - 41t + 78 = 4 (t ² - 41/4 t ) + 78
… = 4 (t ² - 2• 41/8 t + (41/8)² - (41/8)²) + 78
… = 4 (t ² - 2• 41/8 t + (41/8)²) - 4•1681/64 + 78
… = 4 (t - 41/8)² - 433/16
which describes a parabola that opens upward. When t = 41/8 = 5.125, the quadratic term vanishes and the turning point of the parabola occurs at a position of -433/16 units.
If the engine of a car is replaced by one that doubles the amount of net force, the car's acceleration will ___.
Answer:
Double
Explanation:
Newton's second law of motion states that the acceleration of an object is directly proportional to and acts in the same direction as the net force acting on the object. The second law of motion can be represented by the equation:
F ∝ a;
F = ma
where m is the mass which is the constant of proportionality, F is the net force and a is the acceleration of the object.
Hence for a car with a constant mass, if the engine is replace with one that doubles the net force, the acceleration of the car would also double.
A woman of mass 50 kg is swimming with a velocity of 1.6 m/s. If she stops stroking and glides to a stop in the water, what is the impulse of the force that stops her?
Answer:
Impulse of force = -80 Ns
Explanation:
Given the following data;
Mass = 50kg
Initial velocity = 1.6m/s
Since she glides to a stop, her final velocity equals to zero (0).
Now, we would find the change in velocity.
[tex] Change \; in \; velocity = final \; velocity - initial \; velocity [/tex]
Substituting into the equation above;
Change in velocity = 0 - 1.6 = 1.6m/s
[tex] Impulse \; of \; force = mass * change \; in \; velocity [/tex]
Substituting into the equation, we have;
[tex] Impulse \; of \; force = 50 * -1.6[/tex]
Impulse of force = -80 Ns
Therefore, the impulse of the force that stops her is -80 Newton-seconds and it has a negative value because it is working in an opposite direction, thus, bringing her to a stop.
A student in a lab experiment jumps upward off a common bathroom scale as the lab partner records the scale reading. What does the lab partner observe during the instant the student pushes off?
The scale reading will remain unchanged during the entire time the student is in contact with the scale.
The scale reading will increase momentarily then will decrease as the student is moving upward from the scale.
The scale reading will increase during the entire time the student is in contact with the scale.
The scale reading will decrease momentarily then will increase as the student is moving upward from the scale.
Answer:
B: The scale reading will increase momentarily then will decrease as the student is moving upward from the scale
Explanation:
The way weighing scale works is that when you climb on it, it will take your weight reading but when you are moving off the top of it, the reading slowly approaches 0 until you are completely off it.
Thus, the lab partner will observe that the reading will increase for a while and then gradually decrease to zero as the student moves upwards off the scale.
The correct answer is (B)The scale reading will increase momentarily then will decrease as the student is moving upward from the scale.
According to the third law of motion, every action has an equal and opposite reaction. In order to jump, the student will apply force to the bathroom scale in downward direction and there will be an equal force exerted by the bathroom scale upwards on the student which helps him jump.
So when the student applies downward force on the scale in order to jump, the scale reading will increase momentarily and then will decrease as the student moves upwards.
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A ball starts at rest and rolls down an inclined plane. The ball reaches 7.5 m/s in 3 seconds. What is the acceleration?
Answer:
[tex]a=2.5\ m/s^2[/tex]
Explanation:
Motion With Constant Acceleration
It's a type of motion in which the velocity of an object changes uniformly over time.
The equation that describes the change of velocities is:
[tex]v_f=v_o+at[/tex]
Where:
a = acceleration
vo = initial speed
vf = final speed
t = time
Solving the equation for a:
[tex]\displaystyle a=\frac{v_f-v_o}{t}[/tex]
The ball starts at rest (vo=0) and rolls down an inclined plane that makes it reach a speed of vf=7.5 m/s in t=3 seconds.
The acceleration is:
[tex]\displaystyle a=\frac{7.5-0}{3}[/tex]
[tex]\boxed{a=2.5\ m/s^2}[/tex]
Which techniques can scientists use to determine the characteristics of Earth's layers? Select the two correct answers.
conduct experiments about how minerals change under high pressure
study how seismic waves travel through different layers
examine the behavior of minerals at extremely low temperatures
use X-rays to obtain a view of Earth's interior layers
drill deep mines to obtain samples from Earth's mantle and core
Answer:
1 and 3
Explanation:
Scientists can use the following techniques to determine the characteristics of Earth's layers: a) conduct experiments on how minerals change under high pressure; and b) investigate how seismic waves travel through different layers.
Characteristics of Earth's layersMechanically and chemically, the Earth is divided into two categories. The lithosphere, asthenosphere, mesospheric mantle, outer core, and inner core are mechanically separated. However, chemically, which is the more popular of the two, it can be divided into the crust, mantle, and core - which can be further subdivided into outer core and inner core. The outer core is liquid, the inner core is solid, and the mantle is solid/plastic. This is due to the relative melting points of the different layers, as well as the increase in temperature and pressure as depth increases. Because they are cool enough, nickel-iron alloys and silicates are solid at the surface.To learn more about Earth's layers refer :
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PLEASE HELP 100 POINTS
The graph shows the force applied to an object over a displacement of 4 meters. What is the total work done on the object over the 4 meter displacement?
Answer:
okay, So Um,
Explanation:
BTW, There are only 50 points, brainly subtracts half of the points
What are two ways engineers use their understanding of KE and PE to make their designs better / Safer?
Answer:
Follows are the solution to this question:
Explanation:
Energy shifts at such a rollercoaster ride many times throughout a ride from possibility to dramatic power. Kinetic energy is the energy the object provides for its movement. The coaster machine is traditionally lifted by a rope from the very first hill. It gains energy stored because as vehicles move up.
OR
we can say that whenever anyone travels through an amusement park ride often recognized as a ring road, energy transfers from the opportunity to kinetic energy, because of the layout of the curves as well as the slope, and it is replicated few more occasions during the ride.
Kinetic energy seems to be used in motion.
Its amusement ride vehicles were usually climbed back by a rope from the very first hill, but as the other vehicles move along that route, they acquire potential power.
A flat, rigid object oscillates as a physical pendulum in simple harmonic motion with a frequency f. The mass of the pendulum is m, and the pivot point is a distance d from the center of mass. What is the moment of inertia of the pendulum about its pivot point
Answer:
I = mgd/4π²f²
Explanation:
The period of the physical pendulum T = 1/f where f = frequency,
T = 1/f = 2π√(I/mgd) where I = moment of inertia of the physical pendulum, m =mass of pendulum, g = acceleration due to gravity and d = distance of center of mass of pendulum from pivot point.
1/f = 2π√(I/mgd)
dividing both sides by 2π, we have
1/2πf = √(I/mgd)
squaring both sides, we have
(1/2πf) = [√(I/mgd)]²
1/4π²f² = I/mgd
multiplying both sides by mgd, we have
I = mgd/4π²f²
Heat naturally flows from an object that has a _______________ temperature to an object that has a _______________ temperature. Heat can be made to flow in the reverse direction if _______________ is done. A machine can never have an efficiency of _______________. This means that heat energy can never be fully converted into _______________ energy.
Answer:
higher, lower, external work, 100 %, work.
Explanation:
These paragraphs refer to the second law of thermodynamics. There are two statements for the second law of thermodynamics. They are as follows:
KELVIN STATEMENT:
All the heat from a source can never be transferred to the sink without the rejection of some heat.
CLAUSIUS STATEMENT:
Heat can not be transferred from a colder body to a hotter body without the application of som external work.
According to the statements the blanks can be filled as follows:
Heat naturally flows from an object that has a higher temperature to an object that has a Lower temperature. Heat can be made to flow in the reverse direction if external work is done. A machine can never have an efficiency of 100 %. This means that heat energy can never be fully converted into work energy.
Answer:
Heat naturally flows from an object that has a ______high_________ temperature to an object that has a ______lower_________ temperature. Heat can be made to flow in the reverse direction if _______work________ is done. A machine can never have an efficiency of ______100%_________. This means that heat energy can never be fully converted into _______mechanical energy________ energy.
Explanation: This is all derived from the Principles of the Second Law of Thermodynamics.
Kraig pulls a box to the right at an angle of 40 degrees to the horizontal with a force of 30 Newtons. If Kraig pulls the box a distance of 20 meters, determine the work done by Kraig.
Answer:
459.6J
Explanation:
Given parameters:
Angle of pull = 40°
Force applied = 30N
Distance moved = 20m
Unknown:
Work done by Kraig = ?
Solution:
To solve this problem;
Work done = F x dcosФ
d is the distance
F is the force
Ф is the angle given
Work done = 30 x 20cos40° = 459.6J
The voltage across a 5-uF capacitor is: v (t )equals 10 cos open parentheses 6000 t close parentheses space straight V. What is the current through this capacitor?
Answer:
- 0.3sin6000t A
Explanation:
Voltage, v = 10 cos 6000t V
Capacitance = 5-uF
Current flowing through, i(t)
i(t) = c * d/dt (V)
c = 5-uF = 5 * 10^-6 F
i(t) = (5 * 10^-6) * d/dt(10 cos 6000t)
d/dt(10 cos 6000t) = (10 * 6000) * (-sin 6000t)
Hence,
i(t) = (5*10^-6) * (10*6000) * (-sin 6000t)
i(t) = 5*10^-6 * 6*10^4 * - sin6000t
i(t) = 30 * 10^-2 * - sin6000t
i(t) = 0.3*-sin6000t
i(t) = - 0.3sin6000t Ampere
Two resistors are connected in parallel to a 12 V battery. The potential difference across one of the resistors is 12 v . Calculate the potential difference across the other resistor
Answer:
See the explanation below.
Explanation:
We have to take into account that the potential difference is equal to the voltage, and this is measured between two points as the resistors are connected in parallel to the voltage source, the resistors will have the same voltage.
For ease, we will take the attached image of resistors connected in parallel.
As both resistors at their ends share the A & B connection points, these are at a voltage of 12V
Choose all the answers that apply.
Connective tissue
D covers the outside of an organism
hold organs and other tissue in place
lines the inside of holow organs
D cushions the body and stores energy
attaches muscle to bone
joins bones together
Answer:
1. hold organs and other tissue in place
2. Attaches muscles to bone
Explanation:
From its name, the connective tissue has one of its most important functions to be the connection of tissues and organs.
They offer support and connection to other tissues such as tendons that attaches muscles to bones and also skeletons which offers support to the positions of the body.
Connective tissue also offer protection in various forms such as fibrous capsules and also bones that gives protection to delicate organs of the body
An object accelerates 3.0 m/s2 when a force of 6.8 newtons is applied to it. What is the mass of the object?
what's the size of our Galaxy
Answer:
Stellar disk: 185 ± 15 kly (kilo Langley/year)
Dark matter halo: 1.9 ± 0.4 Mly (mega light year) (580 ± 120 kpc)
Explanation:
The Milky Way galaxy contains the sun and the planets orbiting around it. This galaxy also contains up to 400 billion stars. The stellar disk of this galaxy is between 170,000 to 200,000 light years which is equal to a diameter of 52 - 61 kiloparsec.
Its thickness is measured at 0.3kpc which is also equal to 1000 light years. Its mass is 890 billion to 1.54 trillion times the mass of the sun. Its size is second to that of the Andromeda galaxy.
A source of frequency f sends waves of wavelength λ traveling with speed v in some medium. If the frequency is changed from f to 2f, then the new wavelength and new speed are (respectively): Question 1 options:
Answer:
Explanation:
The speed will remain unchanged because speed does not depend upon frequency .
So new speed = v
wavelength x frequency = speed
For frequency = 2 f
wavelength = speed / frequency
= v / 2f
So new wavelength = v / 2f .
1. The new wavelength is equal to [tex]\frac{\lambda}{2}[/tex].
2. The new speed is equal to v.
Given the following data:
Wavelength = λSpeed = vInitial frequency = fFinal frequency = 2fTo determine the new wavelength and new speed are:
Mathematically, the speed of a waveform is calculated by using the formula;
[tex]v = \lambda f[/tex]
Where:
[tex]\lambda[/tex] is the wavelength of a wave.v is the speed of a wave.f is the frequency of a wave.Ideally, the speed of a wave doesn't change when the frequency provided they are both in the same medium.
However, the wavelength would change when frequency changes.
Therefore, the new speed = v.
For new wavelength:
[tex]v = \lambda f=\frac{\lambda}{2} (2f)[/tex]
New wavelength = [tex]\frac{\lambda}{2}[/tex]
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Find the period of a pendulum that has a length of .6m and is on earth. Make sure that you show your work and prominently display the equation that you use to solve it.
Answer:
The period of this pendulum is [tex]T=1.55\: s[/tex]
Explanation:
The equation of motion of a pendulum is given by:
[tex]\frac{d\theta^{2}}{dt^{2}}+\frac{g}{L}sin(\theta)=0[/tex] (1)
Where:
θ is the angle of motion
g is the gravity at the earth surface (9.81 m/s²)
L is the length of the pendulum (0.6 m)
Now, using equation (1) we can find the square angular frequency (ω), it will be:
[tex]\omega^{2}=\frac{g}{L}[/tex]
[tex]\omega=\sqrt{\frac{g}{L}}[/tex]
Let's recall that the angular frequency is [tex]\omega=\frac{2\pi}{T}[/tex], then the period will be:
[tex]T=\frac{2\pi}{\omega}[/tex]
[tex]T={2\pi}\sqrt{\frac{L}{g}[/tex]
[tex]T=2\pi}\sqrt{\frac{0.6}{9.81}[/tex]
Therefore, the period of this pendulum is [tex]T=1.55\: s[/tex]
I hope it helps you!
A tennis ball moves 16 meters northward, then 22 meters southward, then 12 meters northward, and finally 32 meters southward.
Determine the magnitude of the distance the object traveled
Answer:
26 m southwards.
Explanation:
From a North, East, South, West coordinate plane, moving northwards implies positive distance. While moving southwards implies negative distance.
Thus;
It moves 16 meters northward; d = 16 m
It now moves 22 meters southward; d = -22 m
It moves 12 meters northward; d = 12 m
It moves 32 meters southward; d = -32 m
Thus, total magnitude = 16 - 22 + 12 - 32 = -26 m
Thus, the object travels 26 m southwards.
What do light waves NOT do when intereacting with matter
A. Absorbed
B. Reflected
C. Transmitted
D. Dissolve
Answer:
D. Dissolve
Explanation:
A light wave is not a soluble substance, so it cannot dissolve. But it can totally do A, B, and C.
To ____________________ something is to slowly mix in a bit of _____________ ___________________ with eggs or cream to raise the temperature slowly. This prevents the cream from curdling (turning lumpy and gross) or the eggs from scrambling in your sauce.
Answer:
temper; hot sauce
Explanation:
The context clue here is "raise the temperature slowly" gives a quick clue to temper (as a verb). The 4th definition of temper (as a verb) is "to bring to a suitable state by mixing or adding a usually liquid ingredient." Knowning, this leads to the second blank being hot sauce, as that's a liquid.
Coulomb's Law: Coulomb's law is F = k (q1xq2)/ r^2 where k = 9 x 10^9 C^2/m^2. a) Sketch the charges and use Coulomb's law to determine the electric force between two charged particles where q1 = -5 x 10^-3 C and q2 = -1 x 10^-3 C. Q1 and Q2 are separated by a distance of 0.25 m. b) Determine whether the electric force attractive or repulsive and explain your answer?
Answer:
a) F = 7.20 10⁵ N, b) the force between charges is repulsive.
Explanation:
For this exercise we calculate the electric forces given by Coulomb's law
[tex]F = k \frac{q_{1} q_{2} }{r^{2} }[/tex]
where in this case they indicate that q1 = 5 103 C and q2 = 1 103 C and the distance between them r = 0.25 m
let's calculate
F = [tex]9 10^{9} \ \frac{5 \ 10^{-3} \ \ 1 \ 10^{-3} }{0.25^{2} }[/tex]
F = 7.20 10⁵ N
b) when electric charges have the same sign they repel and when they have the opposite sign they attract.
In this case, charge 1 is negative and charge 2 is negative, therefore, since they both have the same sign, the force between charges is repulsive.
Burning can be:
controlled for useful work
stopped for use work
wasted for useful work
Answer:
Controlled for useful work
Explanation:
Here we want to select the option that best describes what burning can be used for
Generally, when we talk about something being burnt, we are referring to the fact that we have the thing being on fire.
So basically, when something is on fire, we can say it is burning. We can harness the burning strength of a particular material or substance to do useful work.
For example, in a fire place in our homes, the burning of wood pieces can be used to heat up our homes. It is this same wood burning that has devastating effects in the bushes which in fact when left uncontrolled can cause degrees of catastrophic damages.
But, by taking the pieces and placing in a fire place in our homes, we have successfully controlled its bad effect and use it to do the useful work of heating up the environment
A force acts on a body of mass 13 kg initially at rest. The force
acts for 10 seconds, and once it quits, the body covers 60 min
the next 6 seconds. Find the force that acted on the body.
Answer:
Force that acted on the body was F = 13 N
Explanation:
If once accelerated, the body covers 60 meters in 6 seconds, then its velocity is 60/6 m/s = 10 m/s
When the force was acting (for 10 seconds) the object accelerated from rest (initial velocity vi = 0) to 10 m/s (its final velocity). therefore we can use the kinematic equation for the velocity in an accelerated motion given by:
[tex]v_f=v_i+a*t[/tex]
which in our case becomes;
[tex]10\,m/s=0+a*(10\,s)[/tex]
and we can solve for the acceleration as:
a = 10/10 m/s^2 = 1 m/s^2
Therefore the force acting on the body, based on Newton's 2nd Law expression: F = m * a is:
F = 13 kg * 1 m/s^2 = 13 N
The picture below shows a man in Varanasi, India, resting on a bed of nails. Which principle about impact force
allows him to do this without getting hurt, and why
Answer:
Since there are hundreds of nails, instead of puncturing your skin the nails actually support you.
Explanation:
If you step on the point of a nail, your foot exerts a tremendous amount of pressure on the nail's tiny point. As a result, the point can go straight through your foot. But a bed of nails has lots of points that are close together -- there's a lot of surface area for the body to cover. Hundreds of nails support the weight of your body instead of just one. Typically, your body doesn't exert enough pressure on any one nail for it to break the skin. You can even place a second bed on top of you and break a cinderblock on it. The resulting force is distributed over all of the nails, so you shouldn't be injured.
The impact force will be less because of the pressure is equally distributed over the body of man. The nails will not puncture his skin.
What is pressure?The pressure of any object is given by the force acting per unit area. When the contact area is less, the object will penetrate.
If one steps on the point of a nail, his foot exerts a tremendous amount of pressure on the nail's contact point. As a result, it will penetrate into the foot. In case of a bed of nails, many nail points placed close together. The surface area for the body to make contact is increased.
Then, hundreds of nails now will support the weight of his body.
Thus, the impact force will be less because of the pressure is equally distributed over the body of man. The nails will not puncture his skin.
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